DiagnosisClinical Diagnosis The diagnosis of chronic granulomatous disease (CGD), a primary immunodeficiency disorder of phagocytes (neutrophils, monocytes, macrophages, and eosinophils) resulting from impaired killing of bacteria and fungi, is suspected in individuals (usually children) with the following findings:Growth retardation in childhood Infections of lung (pneumonia), lymph nodes (lymphadenitis), liver (abscess), bone (osteomyelitis), and skin (abscesses or cellulitis), especially spontaneously occurring severe or recurrent bacterial infections. Microbiologic confirmation of the cause of infection helps confirm the likelihood of CGD, since the spectrum of infection in CGD is distinct and narrow (see Table 2). Granuloma formation, especially genitourinary (bladder) and gastrointestinal (often pyloric initially, and later esophageal, jejunal, ileal, cecal, rectal, and perirectal)Colitis Abnormal wound healing caused by excessive granulation, which may cause the wound to dehisce and gape, leading to healing by secondary intention. TestingClinical tests that rely on direct measurement of neutrophil superoxide production via the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex to establish the diagnosis of CGD include the following: Nitroblue tetrazolium (NBT) test, the oldest and most recognized diagnostic test for CGD, relies on light microscopy to provide a mostly qualitative determination of phagocyte NADPH oxidase activity. When stimulated in vitro, normal phagocytes produce superoxide that reduces yellow NBT to blue/black formazan, forming a precipitate in cells [Baehner & Nathan 1967]. The NBT test is typically performed on a microscope slide, which is read manually to distinguish reducing (blue-black) from non-reducing (unstained) cells: Neutrophils in unaffected non-carriers. More than 95% of cells produce superoxide that reduces NBT to formazan.Neutrophils in individuals with CGD. Production of superoxide is absent or greatly diminished. Female carriers of X-linked CGD (who have two populations of leukocytes). Superoxide is typically produced in 20%-80% of cells [Elloumi & Holland 2007] (range: 0.001%-97%).
Note: Because the NBT test is semi-quantitative and evaluates only a limited number of cells, it may be falsely interpreted as normal: (1) in female carriers of X-linked CGD, especially those with skewed (non-random) X-chromosome inactivation (see Carriers of X-Linked CGD) and (2) in persons with hypomorphic (variant) forms of CGD characterized by partial protein expression/function and residual superoxide production (observed in autosomal recessive CGD and protein-positive X-linked CGD). Dihydrorhodamine (DHR) test uses flow cytometry to measure the oxidation of dihydrorhodamine 123 to rhodamine 123 in phorbol myrisate acetate (PMA)-stimulated neutrophils, a marker for cellular NADPH oxidase activity [Vowells et al 1996]. In this test the generation of hydrogen peroxide oxidizes the dye, leading to the emission of fluorescence. Mean fluorescence intensity of the activated cells correlates directly with (and thus serves as a reliable surrogate for) superoxide production [Kuhns et al 2010].
The DHR test can distinguish the following forms of CGD:Complete forms (i.e., those with absent to greatly diminished production of superoxide) commonly observed in males with X-linked CGD Hypomorphic (variant) forms of CGD characterized by reduced protein expression/function and residual superoxide production (observed in autosomal recessive CGD and protein-positive X-linked CGD).Mosaic forms (i.e., those with two discrete populations of phagocytes: some oxidase-positive and some oxidase-negative) commonly observed in female carriers of X-linked CGD.
Note: Although the pattern of oxidase-positive and oxidase-negative phagocytes can suggest X-linked inheritance of CGD or autosomal recessive inheritance of CGD, the results are not definitive in establishing the mode of inheritance. (See Testing Strategy)Note: Other conditions that may affect the ability of the neutrophil to generate the hydrogen peroxide surge that is detected in the DHR assay include myeloperoxidase deficiency [Mauch et al 2007] and SAPHO (the syndrome of synovitis, acne, pustulosis, hyperostosis, and osteitis) [Ferguson et al 2008]. In these two conditions the DHR results are abnormal, but the levels of superoxide production are normal and NBT staining is normal. Research testsDetermination of residual superoxide function is important in management: patients with little to no superoxide production are at the greatest risk for mortality [Kuhns et al 2010] and, thus, are the most likely candidates for HSCT. The following three tests are performed in research laboratories only:Cytochrome c reduction assay quantitates indirectly the actual amount of superoxide produced by measuring spectrophotometrically the inhibitable reduction of ferricytochrome c by superoxide dismutase to ferrocytochrome c [Elloumi & Holland 2007]. Results of this test correlate well with results of the DHR test. Chemiluminescence. Because superoxide can cause a variety of chemical agents to luminesce, measurement of luminescence (typically using dichlorofluoroscein [DCF]) can quantitate the amount of superoxide produced [Elloumi & Holland 2007]. While this assay can rapidly detect superoxide activity and identify hypomorphic forms of CGD, it lacks cellular resolution and thus cannot identify female carriers of X-linked CGD. Neutrophil superoxide production of reactive oxygen intermediates (ROI). The quantitation of superoxide produced can be obtained directly from the cytochrome c reduction assay (a research laboratory test) or indirectly from the DHR test (a routine clinical test). In general, a DHR test value in the lower range (i.e., <225 arbitrary units) correlates with poor superoxide production, which can be predicted from the specific NADPH oxidase mutation (see Genotype-Phenotype Correlations). Immunoblot test for the NADPH complex proteins. Failure to detect the following cytoplasmic subunits of the phagocyte NADPH oxidase (phox) proteins suggests autosomal recessive inheritance: p47^phox (encoded by NCF1), p67^phox (NCF2), or p40^phox (NCF4) (Table 1 and Table A). Immunoblotting is currently performed only in research laboratories.
Note: This technique cannot distinguish between mutations in CYBB (encoding gp91^phox) and CYBA (encoding p22^phox). Because the protein products of these two genes stabilize each other within the phagocyte membrane absence of one protein results in the absence of the other [Segal et al 2000] (see Molecular Genetics). Mutations in CYBB or CYBA that cause a failure to bind heme (leading to a loss of the cytochrome b558) have been referred to as cytochrome negative. In contrast, mutations in NCF1, NCF2, and NCF4 leave cytochrome b558 intact and have been referred to as cytochrome positive. Because missense mutations in either CYBB or CYBA can also support cytochrome b558 persistence without function, the terminology ‘cytochrome negative’ and ‘cytochrome positive’ is not preferred. Molecular Genetic Testing Genes. CGD is caused by mutation of one of five genes that encode the subunits of phagocyte NADPH oxidase. CYBA, NCF1, NCF2, and NCF4 are the genes in which biallelic mutations cause autosomal recessive chronic granulomatous disease (AR-CGD). CYBB is the gene in which mutations cause X-linked chronic granulomatous disease (X-linked CGD).(See Table A for chromosome loci of these genes and Table 1 and Table A for the protein names and symbols.)Table 1. Summary of Molecular Genetic Testing Used in Chronic Granulomatous Disease View in own windowGene Symbol / Protein Symbol Mode of InheritanceProportion of CGD Attributed to Mutations in This GeneTest MethodMutations DetectedTest AvailabilityCYBA / p22^phox AR6% ^{1Sequence analysisSequence variants 2ClinicalDeletion / duplication analysis 3Exonic or whole-gene deletionsNCF1 / p47phox AR20% 1Targeted mutation analysisc.75_76delGT 4, 5, 6ClinicalNCF2 / p67phox AR6% 1Sequence analysisSequence variants 2ClinicalDeletion / duplication analysis 3Exonic or whole-gene deletionsNCF4 / p40phox AROne individual 7Sequence analysisSequence variants 2ClinicalCYBB / gp91phox XL70% 8Sequence analysis Sequence variants 2, 9ClinicalDeletion / duplication analysis 3Exonic or whole-gene deletions 91. Roos et al [2010a]2. Examples of mutations detected by sequence analysis may include small intragenic deletions/insertions and missense, nonsense, and splice site mutations; typically, exonic or whole-gene deletions/duplications are not detected.3. Testing that identifies deletions/duplications not readily detectable by sequence analysis of the coding and flanking intronic regions of genomic DNA; included in the variety of methods that may be used are: quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), and chromosomal microarray (CMA) that includes this gene/chromosome segment.4. By far the most common mutation in NCF1 is GT deletion c.75_76delGT (ΔGT) at the beginning of exon 2 causing a frameshift and premature stop codon [Kuhns et al 2010, Roos et al 2010a] (see Molecular Genetics).5. Roos et al [2010a] reported that of about 350 affected individuals investigated worldwide, 297 were homozygous for the c.75_76delGT mutation. Of the exceptions, 20 were compound heterozygous for the ΔGT mutation and a second mutation, while 22 had mutations other than c.75_76delGT. 6. Molecular testing for c.75_76delGT can be complicated by nearby pseudogenes (see Molecular Genetics).7. Inactivating mutations in both alleles of NCF4 were reported in one individual [Matute et al 2009] (see Molecular Genetics). 8. Roos et al [2010b]9. In this X-linked gene, sequence analysis can detect small intragenic deletions/insertions, missense, nonsense, and splice site mutations in males and females. Lack of amplification by PCR prior to sequence analysis can suggest a putative exonic or whole-gene deletion on the X chromosome in affected males; confirmation may require additional testing by deletion/duplication analysis. Sequence analysis of genomic DNA cannot detect deletion of one or more exons or the entire X-linked gene in a heterozygous female. Interpretation of test results. For issues to consider in interpretation of sequence analysis results, click here.Information on specific allelic variants may be available in Molecular Genetics (see Table A. Genes and Databases and/or Pathologic allelic variants).Testing Strategy To establish the diagnosis in a proband1.If CGD is suspected clinically, a dihydrorhodamine 123 (DHR) test should be performed. Note: (a) For males, it is useful to test a maternal blood sample simultaneously. (b) Although the pattern of oxidase-positive and oxidase-negative phagocytes can suggest X-linked CGD or autosomal recessive CGD, the results are not definitive in establishing the mode of inheritance. If the patient is a male and the mother’s finding are:Consistent with the carrier state for X-linked CGD, that mode of inheritance is confirmed. Normal, X-linked CGD in her son is not excluded. 2.If results of the DHR test are consistent with the diagnosis of CGD in a proband, the diagnosis of CGD can be confirmed by molecular genetic testing.
Note: The order in which genes are tested may depend on the clinical course, gender, family history, results of the DHR test in the mother of an affected male, and the likelihood that mutation of a given gene is causative (see Table 1). Early onset, more severe infections, and male gender suggest X-linked CGD. Later onset, milder course, female gender, and consanguinity suggest autosomal recessive CGD. 3.If a contiguous gene deletion involving multiple genes at Xp21.1 is suspected based on clinical findings (see Contiguous gene rearrangements), additional clinical testing and/or molecular genetic testing to detect a microdeletion may be warranted. Note: XK, the gene encoding the Kell blood group, is immediately telomeric to CYBB and is the gene most frequently associated with a contiguous deletion involving CYBB; thus, males with X-linked CGD should be tested for the red blood cell Kell antigen, the absence of which is diagnostic of the McLeod neuroacanthocytosis syndrome. Prognostication. Genetic testing is important for prognostication in CGD [Kuhns et al 2010]. In general, NCF1-related CGD (p47phox deficiency) presents a lower risk for infections and mortality than CYBB-related CGD (gp91phox deficiency). Within X-linked CYBB-related CGD, affected males with an allele that produces residual superoxide are at lower overall risk for mortality than those with an allele that produces little or no superoxide. Because the other forms of CGD are relatively uncommon, it is difficult to make specific genotype-phenotype associations; however, the role of superoxide production in influencing disease severity in the two most common forms of CGD (CYBB-related [70%] and NCF1-related [20%]) seems likely to apply to the less common forms of CGD as well. See Genotype-Phenotype Correlations.Carrier testing for at-risk relatives for X-linked CGD requires prior identification of the disease-causing mutation in the family.Note: (1) Carriers are heterozygotes for X-linked CGD and may develop clinical findings of CGD related to the degree of expression of the disease-causing allele that results from X-chromosome inactivation. Normal respiratory burst activity in as few as 10% of cells is sufficient to prevent most severe bacterial and fungal infections; therefore, most carriers have normal host defense. However, some carriers develop clinical evidence of CGD [Johnston 1985], of which the most common findings are cutaneous lesions resembling discoid lupus and recurrent aphthous stomatitis [Hafner et al1992]. (See Carriers of X-Linked CGD)(2) Identification of female carriers requires either (a) prior identification of the disease-causing mutation in the family or, (b) if an affected male is not available for testing, molecular genetic testing first by sequence analysis, and then, if no mutation is identified, by deletion/duplication analysis. Carrier testing for at-risk relatives for autosomal recessive CGD requires prior identification of the disease-causing mutations in the family.Note: Carriers are heterozygotes for this autosomal recessive disorder and are not at risk of developing the disorder.Prenatal diagnosis and preimplantation genetic diagnosis (PGD) for at-risk pregnancies requires prior identification of the disease-causing mutations in the family.Contiguous gene rearrangements. Other genes that lie in close proximity to CYBB at Xp21.1 include [Peng et al 2007]: XK encoding the Kx blood group (telomeric)RPGR encoding retinitis pigmentosa GTPase regulator (telomeric)DMD encoding the protein dystrophin (telomeric)OTC encoding ornithine transcarbamylase (centromeric)Large deletions in Xp21.1 can therefore cause the following disorders in individuals with X-CGD. Note: Concurrent deletion of XK with CYBB is the most common; deletion of all five genes is exceedingly rare.McLeod neuroacanthocytosis syndrome (deletion of XK) is a multisystem disorder with central nervous system (CNS), neuromuscular, and hematologic manifestations in males. CNS manifestations are a neurodegenerative basal ganglia disease including (1) movement disorder, (2) cognitive impairment, and (3) psychiatric symptoms. Neuromuscular manifestations include a (mostly subclinical) sensorimotor axonopathy and clinically relevant muscle weakness or atrophy. The hematologic manifestations are red blood cell acanthocytosis, compensated hemolysis, and the McLeod blood group phenotype resulting from absent expression of the Kx erythrocyte antigen and reduced expression of the Kell blood group antigens. The Kell blood group system can cause strong reactions to transfusions of incompatible blood and severe anemia in newborns of Kell-negative mothers. Heterozygous females have mosaicism for the Kell system blood group antigens and RBC acanthocytosis but lack CNS and neuromuscular manifestations. RPGR-related retinitis pigmentosaDuchenne muscular dystrophy (DMD) Ornithine transcarbamylase deficiency (OTC) leading to urea cycle defects Genetically Related (Allelic) Disorders CYBA, NCF1, NCF2, and NCF4. No other phenotypes are known to be associated with mutations in these four genes.CYBB. Two CYBB missense mutations, NM_000397.3:c.692A>C (p.Gln231Pro) and c.532A>C (p.Thr178Pro), have been associated with susceptibility to mycobacterial disease in two kindreds. The respiratory burst in macrophages was impaired, whereas monocytes and neutrophils showed no dysfunction [Bustamante et al 2011].}

Natural History Chronic granulomatous disease (CGD) is characterized by severe recurrent bacterial and fungal infections and dysregulated inflammatory response resulting in granuloma formation and other inflammatory disorders such as colitis.CGD may present any time from infancy to late adulthood; however, the vast majority of affected individuals are diagnosed before age five years. The median age of diagnosis was 2.5 to three years in several series [Jones et al 2008, Martire et al 2008]. More recently, increased numbers of affected individuals have been diagnosed in adolescence or adulthood. This delay in diagnosis may be attributed to the following: Effective treatment of CGD-related infections with antimicrobials not available in the past Recognition of milder cases of autosomal recessive (AR) CGD that may have gone undiagnosed without currently available tests and/or awareness of milder disease manifestations Overall improvement in food handling and sanitation Infections and granulomatous lesions are usually the first manifestations of CGD, with the most frequent sites being the lung, lymph nodes, and liver. The types of infection seen most often include pneumonia, abscess, adenitis, osteomyelitis, and cellulitis. Other pulmonary complications include empyema and hilar adenopathy. The most common sites for abscesses are the perianal and perirectal areas as well as the liver. Although the frequency of infections in persons with CGD has decreased with the routine administration of antibacterial and antifungal prophylaxis, infections still occur at a frequency of 0.3/year. In North America, the majority of infections in CGD are caused by Staphylococcus aureus, Burkholderia cepacia complex, Serratia marcescens, Nocardia species, and Aspergillus species (Table 2). In other parts of the world important causes of infection are Salmonella, Bacille Calmette-Guerin (BCG), and tuberculosis [Winkelstein et al 2000, van den Berg et al 2009]. Table 2. Infections in CGD: Common Pathogens and Sites of InvolvementView in own windowPathogenPresentationBacterial InfectionsStaphylococcus aureusSoft tissue infections
Lymphadenitis
Liver abscess
Osteomyelitis
Pneumonia
SepsisBurkholderia species ¹
B. cepacia ^{2 B. gladioli B. pseudomalleiPneumonia
SepsisSerratia marcescens 3More common: Osteomyelitis
Soft tissue infections
Less common:
Pneumonia
SepsisNocardia species 4, 5 N. asteroids N. nova N. otitidiscaviarum N. farcinicaPneumonia
Osteomyelitis
Brain abscessGranulibacter bethesdensis 6Necrotizing lymphadenitis
SepsisChromobacterium violaceum 7SepsisFrancisella philomiragia 8SepsisFungal Infections 9Aspergillus species
A. fumigatus A. nidulans A. viridinutans A. flavus A. terreus A. nigerPneumonia
Osteomyelitis
Brain abscess
LymphadenitisPaecilomyces species
P. variotti P. lilacinusPneumonia
Soft tissue infections
OsteomyelitisOther molds
Geosmitha argillacea 10 Cephalosporum species Chaetomium strumarium Phialophora richardsiae Scedosporium apiospermum Exophiala species
Cladosporium species
Zygomycete species
Acremonium species
Neosartorya udagawaePneumonia
Soft tissue infectionYeast InfectionsCandida
C. albicans C. glabrata C. lusitaniaeSepsis
Soft tissue infection
Liver abscessTrichosporon
T. beigeli T. inkinArthrographis kalraePneumonia
Soft tissue infection1. Greenberg et al [2009]2. B. cepacia is also a cause of pneumonia in cystic fibrosis.3. Rosenzweig et al [2008], Friend et al [2009]4. Dorman et al [2002]5. Outside of CGD Nocardia infections occur predominantly in the setting of high dose corticosteroids.6. Greenberg et al [2006]7. Sirinavin et al [2005]8. Mailman & Schmidt [2005]9. Beaute et al [2011], Blumental et al [2011]10. De Ravin et al [2011]Bacterial InfectionsWidespread prophylaxis has limited staphylococcal infections primarily to the skin, lymph nodes, liver, and (rarely) the lung [Holland 2010]. Burkholderia cepacia infection is common in patients with CGD and can occasionally cause sepsis. Outside of CGD Nocardia infections occur predominantly in the setting of high-dose corticosteroids. Mycobacterial diseases in CGD are mostly limited to regional and disseminated BCG infections and tuberculosis. Persons with CGD are less susceptible to nontuberculous infections than persons with defects in T cell or interferon gamma/IL-12 pathways: in persons with CGD, BCG infection causes severe localized disease such as draining skin lesions at sites of BCG vaccination [Lau et al 2008], whereas in persons with severe combined immunodeficiency or defects in the IFN-gamma receptor pathway BCG infection causes disseminated disease.Uncommon bacterial infections that are virtually pathognomonic for CGD include:Granulibacter bethesdensis which causes necrotizing lymphadenitis and sepsis; Chromobacterium violaceum which is found in brackish waters such as the Gulf of Mexico and causes sepsis;Francisella philomiragia which is also found in brackish waters such as the Chesapeake Bay and is a cause of sepsis [Holland 2010]. Bacteremia is relatively uncommon except with certain Gram-negative organisms. Fungal InfectionsInvasive fungal infections, which have the highest prevalence in CGD among all primary immunodeficiencies, were previously the leading cause of mortality in CGD. They occur most commonly in the first two decades of life and can be a first presentation of disease; prevalence of fungal infections is 20%-40% per patient throughout their entire life [Beaute et al 2011]. Fungal infections are typically acquired through inhalation of spores or hyphae resulting in pneumonia that can spread locally to the ribs and spine or metastatically to the brain. Presentation may be insidious with symptoms that are absent or manifest as failure to thrive and malaise. Other common presenting signs and symptoms include cough, fever, and chest pain. Aspergillus species are the most common cause of invasive fungal infections, typically in the lung. Aspergillus fumigatus is the most common of the Aspergillus species to cause of infection in CGD. Although angioinvasion is common in neutropenic settings, it does not occur in CGD. Aspergillus nidulans infection which is almost exclusive to CGD causes more severe and refractory disease with local and distant spread [Beaute et al 2011]. Paecilomyces lilacinus and Paecilomyces variotti cause pneumonia and osteomyelitis in CGD almost exclusively. Mucormycosis has been reported in CGD but seems to only occur in the setting of significant immunosuppression [Vinh et al 2009]. The overall frequency and mortality of invasive fungal infections have been significantly reduced with the use of itraconazole as antifungal prophylaxis and the use of other azoles (voriconazole and posaconazole) as therapy. However, when they occur, fungal infections develop at an older age and may require longer duration of therapy. An increased frequency of infection with Aspergillus nidulans and other opportunistic fungi may be associated with itraconazole prophylaxis [Blumental et al 2011]. Yeast infections are not nearly as common as bacterial and fungal infections in persons with CGD. Note: The endemic dimorphic mold infections histoplasmosis, blastomycosis, and coccidioidomycosis do not occur in CGD [Holland 2010]. Inflammatory and Other ManifestationsFormation of granulomata and dysregulated inflammation in CGD contribute to morbidity and can cause multiple symptoms. The genitourinary and gastrointestinal tracts are most commonly affected. Genitourinary manifestations include bladder granulomata that result in ureteral obstruction and urinary tract infections. Other manifestations include pseudotumors of the bladder and eosinophilic cystitis. Gastrointestinal manifestations Pyloric edema leads to functional gastric outlet obstruction and can be an initial presentation of CGD. Esophageal, jejunal, ileal, cecal, rectal, and perirectal granulomata similar to those in Crohn’s disease have also been described. Symptomatic inflammatory bowel disease affects up to 50% of affected individuals and can be the presenting finding [Marciano et al 2004]. Other gastrointestinal symptoms indicative of CGD colitis include abdominal pain, diarrhea, strictures, and fistulae. Significant colitis leading to bowel obstruction, fistulae, and strictures can be an important cause of growth retardation [Marciano et al 2004].Liver involvement is a significant cause of morbidity in CGD, with abscesses occurring in up to 35% of affected individuals. Liver abscesses have been difficult to cure without surgery and carry a significant risk for recurrence, but not relapse [Hussain et al 2007]. Other common liver abnormalities include liver enzyme elevation, persistent elevations in alkaline phosphatase, and drug-induced hepatitis. High rates of portal venopathy are associated with splenomegaly and nodular regenerative hyperplasia. Portal hypertension and thrombocytopenia are secondary to intrahepatic disease and important risk factors for mortality [Hussain et al 2007, Feld et al 2008]. Hyperinflammation is seen, especially in response to infectious agents. The exact etiology of dysregulated inflammation in CGD is unclear. Heightened inflammatory response has been described in chronic colitis [Marciano et al 2004], granulomatous cystitis [Kontras et al 1971], pulmonary infections with Nocardia [Freeman et al 2011], and staphylococcal liver abscesses [Yamazaki-Nakashimada et al 2006, Leiding et al 2012].Fungi elicit an exuberant inflammatory response regardless of whether the fungi are alive or dead [Morgenstern et al 1997] as in ‘mulch pneumonitis’, a syndrome caused by inhalation of aerosolized decayed organic matter, such as hay or dead leaves [Siddiqui et al 2007]. Acute fulminant pneumonitis (similar to that seen in hypersensitivity pneumonitis) ensues. Prolonged and dysregulated inflammation in CGD can overlap clinically with the syndrome of hemophagocytic lymphohistiocytosis (HLH). HLH is caused by an ineffective and unrestrained inflammatory response by T lymphocytes, NK cells, and macrophages leading to fever, hepatosplenomegaly, cytopenias, and hemophagocytosis in the bone marrow and other tissues. Persons with CGD can develop prolonged fever and most of the clinical features of HLH. Growth retardation is common in CGD and failure to thrive can be a common presenting finding [Marciano et al 2004]. Growth failure can be compounded by colitis. Growth may improve in late adolescence and many affected individuals may attain appropriate adult height and weight, albeit on the lower end of the spectrum.Chronic respiratory disease can result from recurrent infection. Bronchiectasis, obliterative bronchiolitis, and chronic fibrosis may occur but are not as common as in some other primary immunodeficiencies. Ophthalmic manifestations include chorioretinal lesions associated with pigment clumping that are usually asymptomatic. These same lesions have been detected in females who are carriers of a CYBB mutation.Oral manifestations include gingivitis, stomatitis, aphthous ulceration, and gingival hypertrophy. Non-infectious skin manifestations include photosensitivity, granulomatous lesions, vasculitis, and excessive inflammation at drainage and surgical wounds leading to dehiscence.Autoimmune disorders are common. Discoid lupus and systemic lupus erythematosus (SLE) are more common in females who are carriers of a CYBB mutation than in their sons with CGD [Hafner et al 1992]. Other autoimmune diseases reported include idiopathic thrombocytopenic purpura, juvenile idiopathic arthritis, autoimmune pulmonary disease, myasthenia gravis, IgA nephropathy, antiphospholipid syndrome, and recurrent pericardial effusion [Winkelstein et al 2000, De Ravin et al 2008]. Malignancies have been reported in CGD, and appear to be more common in autosomal recessive CGD than in X-linked CGD, raising the possibility that the increased incidence of malignancy is due to other cosegregating autosomal recessive traits [Aguilera et al 2009, Geramizadeh et al 2010, Lugo Reyes et al 2011].The histopathologic patterns of malignancy have significant overlap with certain chronic inflammatory conditions. Of note, the largest series to date reported no malignancies [Winkelstein et al 2000, van den Berg et al 2009]. Survival in CGD has improved greatly, and is now approximately 90% by age ten years [Jones et al 2008, Martire et al 2008, Kuhns et al 2010]. Overall rates of survival are lower among those with X-linked CGD than those with autosomal recessive CGD. Survival is influenced by several factors: Residual superoxide production correlates most directly with overall survival [Kuhns et al 2010] (see Genotype-Phenotype Correlations): Persons with NCF1 (p47phox) mutations have relatively good overall survival (over 80% beyond age 40 years), which is similar to the survival rate in persons with CYBB (gp91phox) missense mutations associated with residual superoxide production. Persons with CYBB (gp91phox) mutations that result in no superoxide production have a survival of about 55% beyond age 40 years. Use of azoles for antifungal prophylaxis and therapy. Several series [Jones et al 2008, Kobayashi et al 2008, Martire et al 2008] report increased survival over the past 20 years with rates of:88%-97% at age 10 years73%-87% at age 20 years46%-55% at age 30 years
Note: Patients diagnosed and treated before the use of azoles usually did not survive past age 30-40 years.Access to care and expertise of caregivers Post-infectious complications such as hepatic nodular regenerative hyperplasia and portal venopathy associated with liver abscess, which contribute to overall morbidity and mortality [Marciano et al 2004, Hussain et al 2007, Feld et al 2008]. Note: Inflammatory bowel disease does not influence mortality: overall survival rates of persons with CGD with and without colitis are similar [Marciano et al 2004]. Hypomorphic (variant) CGD is characterized by partial protein expression/function and residual superoxide production (observed in autosomal recessive CGD and protein-positive X-linked CGD). Affected individuals typically have a milder course and come to clinical attention later in life than those with complete defects [Bender et al 2009]. Carriers of X-Linked CGD Female carriers of a CYBB mutation are typically unaffected as the amount of gp91phox produced by their second (normal) CYBB allele allows adequate superoxide production. However, some women are affected because they express primarily the CYBB disease-causing allele as the result of skewed (non-random) X-chromosome inactivation. These women may develop clinical evidence of CGD [Johnston 1985, Anderson-Cohen et al 2003]: The most common findings are cutaneous lesions resembling discoid lupus and recurrent aphthous stomatitis [Hafner et al 1992]. In a prospective study of 19 women known to be CYBB mutation carriers, Cale et al [2007] found a history of photosensitive skin rashes (58%), mouth ulcers (42%), and joint pain (37%). Most of these women had negative lupus serology. Lewis et al [2008] reported a female age 16 years with X-linked CGD in whom methylation analysis demonstrated skewed X-chromosome inactivation resulting in expression of the CYBB mutation inherited from her mother. Gono et al [2008] reported a woman age 28 years with CGD resulting from a de novo CYBB mutation on her paternally inherited X chromosome and skewed X-chromosome inactivation of her maternally inherited X chromosome.Wolach et al [2005] report somatic mosaicism for a CYBB mutation in a woman with findings consistent with X-linked CGD at age 66 years. They suggested that the mutation probably originated in her bone marrow.}

Genotype-Phenotype Correlations Historically, it has been recognized that mutations in CYBB (the cause of X-linked CGD) give rise to a more serious phenotype than mutations causing autosomal recessive (AR) forms of CGD. Compared to persons with AR-CGD, males with X-linked CGD are typically diagnosed earlier and have a significantly higher incidence of perirectal abscess, suppurative adenitis, gastric outlet obstruction, urinary obstruction; and higher mortality at a young age. Genotype-phenotype correlations in the X-linked gene CYBB (encoding gp91^phox) include the following:All nonsense mutations or deletions of CYBB in males are highly deleterious and associated with poorer outcomes. Missense mutations that occur in the CYBB region encoding amino acids 1-309 are associated with residual superoxide production at a level sufficient for good overall survival. Exceptions are mutations in the nucleotides encoding histidine at residue 222, which do not support production of residual superoxide and, therefore, are more deleterious. CYBB regions encoding amino acid residues 310 and beyond affect the FAD and NADPH binding domains that are essential for superoxide function. Even when mutations in this region allow protein expression, the proteins are nonfunctional and associated with poorer overall outcomes in affected males. Therefore, protein expression is neither a reliable nor useful predictor of residual superoxide production [Kuhns et al 2010]. The phenotype caused by mutations in CYBB associated with residual superoxide production can be referred to as variant (hypomorphic) CGD, characterized often by later onset, milder course, and better survival than classic X-linked CGD. Of note, the presence or absence of inflammatory bowel disease does not seem to correlate with superoxide production in persons with X-linked CGD [Bender et al 2009].Kuhns et al [2010] detemined that the level of residual neutrophil superoxide production influences morbidity and survival rates in persons with CGD. The production of reactive oxygen intermediates (ROI) was measured using the cytochrome c reduction assay (see Testing, Research tests) and the DHR test (see Testing, Clinical tests). Protein expression was determined using the immunoblot test for the NADPH complex proteins (see Testing, Research tests). Persons with modest ROI production have less severe illness and higher long-term survival than those with little ROI production. ROI production may be predicted by the specific mutation type and gene. Lower ROI production associated with decreased survival was observed in persons with deletions and nonsense, frameshift, and splice mutations. Higher ROI production and increased survival was observed in persons with CYBB missense mutations (with the exception of histidine 222) or mutations in CYBA, NCF1, and NCF2 [Kuhns et al 2010].Of note, complete CYBA mutations disable the cytochrome and therefore behave similarly to severe CYBB mutations; however, as few individuals with severe disease caused by CYBA mutations have been reported, it is not possible to draw conclusions regarding statistical significance.

Differential DiagnosisThe differential diagnosis of chronic granulomatous disease (CGD) mainly involves disorders with recurrent or unusual infections or disorders associated with granuloma formation and hyperinflammation. The following disorders should be considered:Cystic fibrosis. Individuals with cystic fibrosis may develop infections with Burkholderia cepacia complex. Unlike the infections in CGD, these infections are typically isolated to the lung and occur concurrently with significant bronchiectasis. Individuals with CGD are prone to recurrent infection with different strains of pulmonary Burkholderia cepacia complex, whereas those with cystic fibrosis are often persistently infected with the same strain [Greenberg et al 2009]. Hyper IgE syndrome. Staphylococcal and Aspergillus infections are common in individuals with hyper IgE syndrome. However, those with hyper IgE syndrome also have characteristic facies, skeletal abnormalities, and markedly elevated IgE [Freeman & Holland 2009]. Allergic bronchopulmonary aspergillosis (ABPA). ABPA is a hypersensitivity reaction to exposure to Aspergillus fumigatus in the lungs and is most commonly seen in asthmatics and persons with cystic fibrosis. The diagnosis is based on history, elevated serum concentration of IgE, blood eosinophilia, immediate skin reactivity to Aspergillus fumigatus antigens, presence of precipitating serum antibodies to Aspergillus fumigatus, and specific imaging results, none of which are characteristic of CGD [Greenberger 2002]. Glucose 6-phosphate dehydrogenase (G6PD) deficiency and glutathione synthetase (GS) deficiency. Deficiencies in G6PD and GS affect the neutrophil respiratory burst and can increase host susceptibility to infections. Both disorders are associated with hemolytic anemia; GS deficiency is associated with 5-oxoprolinuria and intellectual disability, features not seen in CGD [Whitin & Cohen 1988, Ristoff et al 2001]. Crohn’s disease. Significant colitis leading to bowel obstruction, fistulae, and strictures can occur in patients with CGD and can be an important cause of growth retardation [Marciano et al 2004]. Persons with Crohn’s disease also can present with weight loss, abdominal pain, diarrhea, and colitis. Other. Spontaneously occurring severe or recurrent bacterial infections should always prompt consideration of immune deficiency. Persons with recurrent soft tissue infections or staphylococcal lymphadenitis should be evaluated for CGD. Presence of liver abscess or other deep tissue abscesses is concerning for CGD as well as other immunodeficiencies. Note to clinicians: For a patient-specific ‘simultaneous consult’ related to this disorder, go to , an interactive diagnostic decision support software tool that provides differential diagnoses based on patient findings (registration or institutional access required).AR-CGD, cytochrome b-positiveAR-CGD, cytochrome b-negativeX-CGD

ManagementEvaluations Following Initial Diagnosis To establish the extent of disease and needs of an individual diagnosed with chronic granulomatous disease (CGD), evaluation should include the following: Molecular genetic testing to identify the gene in which mutation is causative and the specific type of mutation, which may provide important prognostic data [Kuhns et al 2010] (See Genotype-Phenotype Correlations.)Tests looking for evidence of infection, such as C reactive protein (CRP) and erythrocyte sedimentation rate (ESR), sensitive but non-specific markers of inflammationComplete blood count (CBC). Anemia is usually present either due to anemia of chronic disease or iron deficiency anemia. Poor iron absorption is common in CGD-related colitis.Albumin. Hypoalbuminemia is found in 70% of persons with GI involvement and in 25% of persons without GI manifestations [Marciano et al 2004]. Endoscopy and colonoscopy if signs and symptoms of colitis are present Imaging as it pertains to specific symptoms for diagnosis and management of infection. Because CGD can affect every organ system different radiologic modalities can be used depending on the site of infection. Because of its relative ease and sensitivity, CT scan is often used; however, ultrasound and MRI can be used instead in many instances. Affected Organs / Manifestations of CGD on Imaging Lungs / pneumonia [Godoy et al 2008]CXR. Consolidation, reticular nodular opacities, scarringCT. Consolidation, ground-glass opacity, tree-in-bud opacity, centrilobular or random nodules, septal thickening, air trapping, scarringEmpyema or abscessMediastinal or hilar adenopathy, honeycomb lung, pleural thickening in chronic casesContiguous spread to chest wall, associated osteomyelitis of ribs and vertebral bodiesLymph nodes / suppurative adenitis [Towbin & Chaves 2010]CT. Enhancing lymph node with central area of hypodensity and enhancing septationsUS. Swirling debris, thickened septa, and increased color Doppler flowCalcifications if granuloma presentLiver / abscess [Garcia-Eulate et al 2006]Single to multiple small or large abscesses, sharply defined; variable enhancement but usually with small central area with poor enhancementCalcificationsMusculoskeletal / osteomyelitis [Galluzzo et al 2008]Multifocal, occurring in ribs, vertebral bodies, small bones of hands and feetGenitourinary / cystitis [Walther et al 1992]Inflammatory pseudotumors of the bladder; on US appear as focal wall thickeningGastrointestinal / obstruction and colitis [Marciano et al 2004, Laskey et al 2009]ObstructionEsophagus: strictures, diverticula, dysmotilityThickening of bowel wall, fistulaeUpper GI: gastric outlet obstruction with gastric dilation, delayed gastric emptying, circumferential antral narrowing, thickened gastric foldsUS, CT, or MRI. Gastric wall thickeningColitis Bowel wall thickening, skip lesions, luminal narrowing, fistulae, cobblestone mucosal patternHead and neck / sinusitis [Towbin & Chaves 2010]MRI. Fungal sinusitis hypointense on T₁ and T₂-weighted images, associated with bony destructionCT. Fungal sinusitis hyperdenseCentral nervous system / abscess [Towbin & Chaves 2010]Abscesses with typical appearance on MRI with ring enhancing lesionsTreatment of ManifestationsSerious infections may occur at any time in persons with CGD. Infections that are asymptomatic or minimally symptomatic may be identified at initial presentation. Significant rises in CRP or ESR should prompt evaluation for infection. Imaging is important in detection and understanding the severity of infections. CT or MRI should be followed closely until resolution of infections. A definitive microbiologic diagnosis is essential to proper treatment of infections. Biopsies to identify the pathogen should be pursued prior to initiation of antimicrobial therapy unless infections are life threatening. Often obtaining an appropriate sample for diagnosis requires fine needle aspiration or percutaneous drainage of an abscess. Initially antibiotics and antifungals are often used empirically with more selective use after the pathogen is identified. Newer azole drugs (voriconazole and posaconazole) have expanded therapeutic options for fungal infections in CGD. Long courses of antimicrobials are often needed for adequate treatment. For example, those who do develop fungal infections on itraconazole prophylaxis develop them at an older age and may require longer duration of therapy. Of note, the primary prophylaxis used to prevent bacterial and fungal infections also has good activity against yeast; however, should yeast infections occur, treatment with organism-specific antimicrobials is warranted.Percutaneous drainage itself can be therapeutic especially for liver or other intra-abdominal abscesses. Lymphadenitis and liver abscesses often require excisional surgery [Feld et al 2008]; however, staphylococcal liver abscesses can be treated with drainage, antimicrobials, and corticosteroids, avoiding surgical excision [Leiding et al 2012]. Colitis. Treatment of colitis in CGD can be difficult. Corticosteroids are usually effective but have long-term complications including growth retardation, osteoporosis, and increased risk of infection. The authors’ current practice is to initiate therapy for proven colitis with prednisone 1 mg/kg/day for one to two weeks followed by a slow taper to 0.1-0.25 mg/kg/day over one to two months [Holland 2010].Metronidazole for prophylaxis against bowel flora, salicylic acid derivatives, 6-mercaptopurine, and mesalamine are also useful in treatment of CGD colitis. Use of TNF-alpha inhibitors, specifically infliximab, a chimeric (mouse/human) monoclonal antibody to TNF alpha, is successful in closing fistulae but leads to increased frequency of severe infections with typical CGD pathogens or death. A report of infliximab in five persons with CGD was associated with severe infections in all five and death in two. Of note, none of the five developed mycobacterial infections, as has been reported with use of infliximab in other conditions [Uzel et al 2010]. Successful bone marrow transplantation appears to cure CGD and the related colitis [Kang et al 2011].Corticosteroid treatment of heightened inflammatory response. Simultaneous administration of antimicrobials and corticosteroids can help resolve the infections and extensive areas of inflammation which can occur with chronic colitis [Marciano et al 2004], granulomatous cystitis [Kontras et al 1971], pulmonary infections with Nocardia [Freeman et al 2011], and staphylococcal liver abscesses [Leiding et al 2012]. Successful treatment of fungi that elicit an exuberant inflammatory response requires the simultaneous administration of antifungals and corticosteroids [Siddiqui et al 2007]. Aggressive treatment of the syndrome of hemophagocytic lymphohistiocytosis (HLH) with antimicrobials, IVIg, and steroids can lead to clinical improvement and remission [Parekh et al 2011]. Because the HLH-like syndrome in CGD represents a reaction to bacterial or fungal infection, these infections must be aggressively treated if patients receive immunosuppression for HLH. Although the merit of immunosuppression in the setting of infection-triggered HLH in CGD is unclear, treatment of the infection is essential.Granulocyte infusions. The value of granulocyte infusions has not been evaluated in prospective controlled trials; however, multiple case reports suggest its utility in treating serious bacterial and fungal infections [von Planta et al 1997, Ozsahin et al 1998, Bielorai et al 2000, Ikinciogullari et al 2005]. The principle that a small number of normal phagocytes may be able to compensate for the oxidative defect in CGD phagocytes supports the use of granulocyte infusions in CGD. Transfused granulocytes have been recovered from sites of infection and appear to have normal respiratory burst activity and to traffic normally. Granulocyte infusions are generally well tolerated; however, adverse effects include fever, development of leukoagglutinins, and rarely, pulmonary leukostasis. Development of alloimmunization is a major concern for patients under consideration for hematopoietic stem cell transplantation (HSCT) [Heim et al 2011]. The possibility of CMV transmission is also a cause for caution.Males with X-Linked CGDFor males with X-linked CGD and McLeod neuroacanthocytosis syndrome early consideration should be given to autologous blood banking (see also Testing Strategy, Contiguous gene rearrangements). Persons with McLeod neuroacanthocytosis syndrome do not express the erythrocyte blood group Kell antigen (i.e., they are Kell-negative). Should they require transfusion of blood products, Kell-positive blood products must be avoided in order to prevent a transfusion reaction. Kell-negative blood products are rarely available. Prevention of Primary ManifestationsAntibacterial prophylaxis. No randomized prospective clinical trials of antibacterial prophylaxis in persons with CGD have been performed; however, several retrospective studies suggest that trimethoprim-sulfamethoxazole (TMP-SMX) is effective in preventing bacterial infections. Lifelong daily antibacterial prophylaxis with oral TMP-SMX is recommended at 5 mg/kg up to 320 mg administered in two divided doses. Note: In liquid TMP-SMX the concentration of TMP is 40 mg/5 mL and sulfamethoxazole 200 mg/5 mL; the therapeutic dose of TMP-SMX is determined by the TMP component. Alternatives to TMP-SMX for patients allergic to sulfonamides include trimethoprim as a single agent, dicloxacillin, cephalosporins, and fluroquinolones. Antifungal prophylaxis. The use of azole antifungal drugs has markedly reduced the frequency and severity of fungal infections in CGD. Lifelong antifungal prophylaxis with itraconazole 5 mg/kg oral solution to a maximum of 200 mg once daily is recommended [Gallin et al 2003]. In a randomized trial, 39 patients were assigned to receive either placebo or itraconazole (100 mg/day in those ages 5-12 years and 200 mg/day in those ages >13 years and weight >50 kg); only one person receiving itraconazole had a serious fungal infection compared to seven in the placebo group [Gallin et al 2003]. For those unable to tolerate itraconazole, posaconazole 200 mg three times daily has been studied in the oncology setting and is likely to be effective in CGD as well [Segal et al 2005]. Of note, the primary prophylaxis used to prevent bacterial and fungal infections also has good activity against yeast.Immunomodulatory therapy. Interferon gamma (IFN-gamma) has become part of the prophylactic regimen in most centers in the United States; however, opinions differ on its use as primary prophylaxis and in the treatment of acute infections. The exact mechanism of IFN-gamma in CGD is not known, adding to the debate over its utility. An international multicenter randomized prospective placebo-controlled trial showed a decrease in rate of serious infections in the group receiving IFN-gamma (22%) versus placebo (46%) after a follow-up period of 8.9 months. This improvement was independent of age, CGD genotype, or concomitant use of other prophylactic antibiotics. Three prospective Phase IV trials showed decreased rates of infections ranging from 0.13-0.4 per patient year. However, one prospective study comparing treatment with TMP-SMX and itraconazole alone versus addition of IFN-gamma showed no difference in the rates of infection [Martire et al 2008]. Some practitioners use IFN-gamma only in the setting of acute infection, rather than as primary prophylaxis. The data for this are anecdotal and unimpressive. The authors typically discontinue IFN-gamma during acute infection, as its utility is unclear and the exacerbation of malaise and fever can confuse the clinical picture and alter decision-making [Holland 2010]. Administration by injection, cost, and lack of familiarity with cytokine therapy all affect the use of IFN-gamma in CGD. The authors use IFN-gamma (50 mcg/m² subcutaneously three times per week) as prophylaxis [Holland 2010]. Fever, myalgias, and malaise are the most common side effects but can be alleviated with concurrent administration of acetaminophen. Hematopoietic stem cell transplantation (HSCT). Allogeneic HSCT is the only known cure for CGD. Historically, HSCT has been associated with high morbidity and mortality and thus reluctantly offered. However, the use of non-myeloablative conditioning regimens has greatly decreased the risk of regimen-related toxicity as well as allowing for transplantation in the setting of active infection; recent reports place transplant survival at 90%-95% [Gungor 2010, Kang et al 2011] with roughly equal survival among patients with matched related, matched unrelated, and umbilical cord blood donors. The issue of which individuals with CGD should undergo HSCT remains complex. While transplant-related mortality rates have fallen dramatically and successful cure has risen, issues of long-term risk, sterility, graft-versus-host disease, donor matching, expense, center experience, availability, and insurance coverage all strongly influence family and physician choices regarding transplantation. Levels of residual superoxide production have correlated well with overall survival [Kuhns et al 2010] (i.e., individuals with very low superoxide production had worse long-term survival than those with higher levels of superoxide production), suggesting that this latter group could benefit more from transplantation. However, even within this group some patients do relatively well for long periods. Patients with CGD may experience behavioral, emotional, and learning difficulties as a consequence of chronic disease, recurrent hospitalization, and limitations of activity. Older children and adolescents are especially likely to be non-compliant with respect to prophylaxis and risk avoidance, increasing their risk for CGD-related complications. The inflammatory bowel disease present up to 50% of persons with X-linked CGD may result in discomfort and growth impairment, and may require colostomy or colectomy. Thus, with improved outcomes HSCT presents an increasingly reasonable alternative and the possibility of a normal life. As HSCT becomes more available it will likely be a first and early choice for the management of CGD. Currently, many centers offer HSCT after the first life threatening infection, but with advances in the technique, the availability of donors, especially for minority populations, and the availability of experienced centers, that timing may change. However, even without HSCT the majority of persons with CGD will live into adulthood. Aggressive prophylaxis and infection management increase the likelihood of doing well.SurveillanceRegular follow-up visits can aid in early detection and treatment of asymptomatic or minimally symptomatic infections and non-infectious complications such as colitis, pulmonary granulomas, and pulmonary fibrosis [Roesler et al 2005]. Laboratory examinations include CBC, chemistries, CRP, and ESR. Significant rises in CRP or ESR should prompt evaluation for infection. Presence of microcytic anemia and hypoalbuminemia may indicate development of colitis. Although imaging is also important in detection of infectious and non-infectious manifestations, no specific guidelines address the intervals at which imaging should be used. CT or MRI should be followed closely to follow progression of disease or until resolution of infections. Frequent follow-up visits also provide the treating clinician opportunities to encourage compliance with prophylaxis and educate the patient and family about the disease. Agents/Circumstances to AvoidActivities that expose the affected person to decayed organic matter (e.g., mulching, gardening, leaf raking, house demolition) are to be avoided as inhalation of fungal spores can result in fulminant pneumonitis leading to hypoxia and respiratory failure [Siddiqui et al 2007].Persons with CGD and McLeod neuroacanthocytosis syndrome lack red blood cell Kell antigens and, therefore, should not receive blood transfusions that are Kell antigen positive.Evaluation of Relatives at RiskEarly diagnosis of relatives at risk allows prompt initiation of antimicrobial prophylaxis and other treatment. The two options for identification of affected relatives are:Molecular genetic testing either prenatally or immediately after birth of (1) at-risk males in a family with a known CYBB disease-causing mutation or (2) at-risk sibs in a family with known CYBA, NCF2, NCF1, and NCF4 mutations;If the disease-causing mutation(s) in the family are not known, the DHR test.See Genetic Counseling for issues related to testing of at-risk relatives for genetic counseling purposes.Pregnancy ManagementThe major concern during the pregnancy of a woman known to have CGD is continued use of prophylactic antimicrobials. Trimethoprim, a folic acid antagonist, is usually avoided in pregnancy for this reason. Sulfamethoxazole is not known to increase the risk of birth defects in humans; however, it is typically administered in conjunction with trimethoprim for prophylaxis in affected non-pregnant women.Data regarding teratogenicity of itraconazole are limited. Although case reports of birth defects in infants born to women taking itraconazole during pregnancy have been published, this observation is not supported by larger case series. Given the lack of adequate data on the use of itraconazole during pregnancy, some practitioners suggest that it should be avoided during pregnancy until such data become available. The authors’ practice is to transition a pregnant woman with CGD to alternative antibacterial prophylaxis, such as penicillin- or cephalosporin-based therapies, for which more data on safety during pregnancy exist [Author, personal communication]. Although no antifungal prophylactic medications known to be completely safe during pregnancy are currently available, the risks and benefits of antifungal treatment must be weighed case by case. Therapies Under InvestigationGene therapy. CGD is an attractive target for gene therapy since it results from a single gene defect, neutrophil superoxide production can be reconstituted in vitro, and correction of neutrophil superoxide production need not be complete to provide complete protection, as exemplified by X-linked carriers. Although initially unsuccessful, more recent gene therapy efforts have been encouraging. Kang et al [2010] recently reported that all three individuals with X-linked CGD who underwent gene therapy (introduction of a vector containing a normal CYBB into a subset of their CD34 cells) showed evidence for presence of the normal CYBB gene and two had a very low-level correction of neutrophil superoxide production. One had resolution of infection with 1.1% of neutrophils regaining gp91^phox expression. There is no known survival advantage for corrected CGD cells in the bone marrow or other tissues, further complicating the already low rates of reconstitution of treated cells, and all patients lost significant levels of cells containing the corrected gene over the course of several months. Gene therapy in CGD has also been complicated by the development of hematologic malignancies in treated individuals [Ott et al 2006, Stein et al 2010]. Two adults who were successfully treated with retrovirus-based therapy (i.e., a clinical response was observed post treatment) developed monosomy 7 secondary to retroviral insertional activation of transcription of the oncogene MECOM (MDS and EVI1complex locus). Search ClinicalTrials.gov for access to information on clinical studies for a wide range of diseases and conditions.

Molecular GeneticsInformation in the Molecular Genetics and OMIM tables may differ from that elsewhere in the GeneReview: tables may contain more recent information. —ED.Table A. Chronic Granulomatous Disease: Genes and DatabasesView in own windowGene SymbolChromosomal LocusProtein NameLocus SpecificHGMDCYBBXp11​.4Cytochrome b-245 heavy chainCatalogue of Somatic Mutations in Cancer (COSMIC)
Resource of Asian Primary Immunodeficiency Diseases (RAPID)
CYBB homepage - Mendelian genesCYBBNCF17q11​.23Neutrophil cytosol factor 1Resource of Asian Primary Immunodeficiency Diseases (RAPID)
NCF1 homepage - Mendelian genesNCF1CYBA16q24​.3Cytochrome b-245 light chainResource of Asian Primary Immunodeficiency Diseases (RAPID)
CYBA homepage - Mendelian genesCYBANCF21q25​.3Neutrophil cytosol factor 2Resource of Asian Primary Immunodeficiency Diseases (RAPID)
NCF2 homepage - Mendelian genesNCF2NCF422q12​.3Neutrophil cytosol factor 4 NCF4Data are compiled from the following standard references: gene symbol from HGNC; chromosomal locus, locus name, critical region, complementation group from OMIM; protein name from UniProt. For a description of databases (Locus Specific, HGMD) to which links are provided, click here.Table B. OMIM Entries for Chronic Granulomatous Disease (View All in OMIM) View in own window 233690GRANULOMATOUS DISEASE, CHRONIC, AUTOSOMAL RECESSIVE, CYTOCHROME b-NEGATIVE 233700GRANULOMATOUS DISEASE, CHRONIC, AUTOSOMAL RECESSIVE, CYTOCHROME b-POSITIVE, TYPE I 233710GRANULOMATOUS DISEASE, CHRONIC, AUTOSOMAL RECESSIVE, CYTOCHROME b-POSITIVE, TYPE II 300481CYTOCHROME b(-245), BETA SUBUNIT; CYBB 306400GRANULOMATOUS DISEASE, CHRONIC, X-LINKED; CGD 601488NEUTROPHIL CYTOSOLIC FACTOR 4; NCF4 608508CYTOCHROME b(-245), ALPHA SUBUNIT; CYBA 608512NEUTROPHIL CYTOSOLIC FACTOR 1; NCF1 608515NEUTROPHIL CYTOSOLIC FACTOR 2; NCF2 613960GRANULOMATOUS DISEASE, CHRONIC, AUTOSOMAL RECESSIVE, CYTOCHROME b-POSITIVE, TYPE IIIMolecular Genetic Pathogenesis Chronic granulomatous disease is a single phenotype caused by mutation in one of five genes that encode proteins of NADPH oxidase. The genes and the official names of their protein products are listed in Table A. However, the protein components are generally known by the names of gp91^phox (encoded by CYBB) and p22^phox (CYBA), which are membrane bound and p47^phox (NCF1), p67^phox (NCF2), and p40^phox (NCF4), which are cytoplasmic. CYBANormal allelic variants. CYBA sequence NM_000101.2 comprises six exons. Pathologic allelic variants. Roos et al [2010a] reported 55 different mutations in 96 individuals from 87 families. The majority were missense mutations (34.6%) followed by deletions (29.1%), splice site mutations (20.0%), nonsense mutations (12.7%), and insertions (3.6%). Compound heterozygotes have been reported [Kuhns et al 2010].Normal gene product. Cytochrome b comprises a light chain (alpha subunit) and a heavy chain (beta subunit). CYBA encodes the alpha subunit which has been proposed as a primary component of the microbicidal oxidase system of phagocytes (provided by RefSeqGene, December 2011).As noted in Testing, Research tests, the cytochrome b-245 light chain (p22^phox) and cytochrome b-245 heavy chain (gp91^phox; encoded by CYBB) presumably stabilize each other in the phagocyte membrane. Abnormal gene product. In all mutation-positive cases in which p22^phox expression was evaluated, protein expression was absent except in the instance of one missense mutation in which proline was replaced with glycine at position 156 [Roos et al 2010a].CYBBNormal allelic variants. CYBB sequence NM_000397.3 comprises 13 exons. CYBB was previously known as NOX2. Pathologic allelic variants. In a recent update of hematologically important mutations causing X-linked CGD, Roos et al [2010b] reported a total of 681 mutations of which the majority were nonsense mutations (29.8%) followed by deletions (22.2%), splice site mutations (19.5%), missense mutations (19.4%), insertions (1.5%), deletions/insertions (1.5%), and promoter mutations (0.6%). Two missense mutations in CYBB have been described with an exclusive association to susceptibility to mycobacterial disease. These mutations preserved superoxide production in neutrophils and monocytes but impaired superoxide production in macrophages and B cells (see Genetically Related Disorders). Normal gene product. Cytochrome b comprises a light chain (alpha subunit) and a heavy chain (beta subunit). CYBB encodes the cytochrome b-245 beta subunit. As noted in Testing, Research tests, the cytochrome b-245 light chain (p22^phox; encoded by CYBA) and cytochrome b-245 heavy chain (gp91^phox) presumably stabilize each other in the phagocyte membrane. Abnormal gene product. In all affected males with CYBB mutations where gp91^phox expression was evaluated, protein expression was absent or decreased [Roos et al 2010b]. NCF1Normal allelic variants. The NCF1 sequence NM_000265.4 comprises 11 exons.Pathologic allelic variants. The presence of two pseudogenes, NCF1B and NCF1C, which are more than 98% homologous to the functional NCF1, has complicated the identification of other mutations in NCF1. Recombination events between NCF1 and flanking pseudogenes with the deletion c.75_76delGT result in the incorporation of the deletion into the NCF1 allele [Gorlach et al 1997]. A GT dinucleotide deletion (c.75_76delGT) at a GTGT tandem repeat is the most common CGD-causing allele in the population, with a carrier frequency of 1:250. The new mutation in the functional NCF1 allele (c.75_76delGT) is at the beginning of exon 2 and results in a frameshift and premature stop codon. Table 3. NCF1 Pathologic Allelic Variants Discussed in This GeneReviewView in own windowDNA Nucleotide Change Protein Amino Acid ChangeReference Sequencesc.75_76delGT (ΔGT)p.(Tyr26Hisfs*26)NM_000265​.4
NP_000256​.3See Quick Reference for an explanation of nomenclature. GeneReviews follows the standard naming conventions of the Human Genome Variation Society (www​.hgvs.org). Normal gene product. The protein p47^phox encoded by NCF1 is a 47-kd cytosolic subunit of the multi-protein NADPH oxidase complex found in neutrophils. Abnormal gene product. In all affected individuals with NCF1 mutations where p47^phox expression was evaluated, protein expression was absent [Roos et al 2010a].NCF2Normal allelic variants. Alternative splicing of NCF2 results in multiple transcript variants encoding different isoforms. The NCF2 transcript variant NM_000433.3 comprises 15 exons.Pathologic allelic variants. A total of 54 different mutations in 95 individuals from 83 families have been described [Roos et al 2010a]. The majority were missense mutations (31.5%) followed by deletions (25.9%), splice site mutations (20.4%), nonsense mutations (14.8%), and insertions (7.4%). Normal gene product. NCF2 encodes neutrophil cytosolic factor 2, the 67-kd cytosolic subunit of the multi-protein NADPH oxidase complex found in neutrophils. The protein is often designated as p67^phox.Abnormal gene product. In all affected individuals with NCF2 mutations where p67^phox expression was evaluated, protein expression was absent or decreased except for one deletion of lysine at amino acid 196 and one deletion of lysine at amino acid 58 [Roos et al 2010a]. NCF4Normal allelic variants. Alternatively spliced transcript variants encoding distinct isoforms have been observed. NCF4 transcript variant NM_013416.3 is the longest and comprises nine exons. Pathologic allelic variants. Mutations in NCF4 have been reported in a single case [Matute et al 2009]. A duplication of base pairs 143-152 led to premature truncation of the protein. A missense mutation (Arg105Gln) on the other allele supported production of a non-functional p40^phox protein.Normal gene product. The protein encoded by NCF4 is a cytosolic regulatory component of the superoxide-producing phagocyte NADPH-oxidase, a multicomponent enzyme system important for host defense. NM_013416.3 encodes the longest isoform NP_038202.2, which has 348 amino acid residues. Abnormal gene product. In the one reported affected individual NCF4 mutations predicted a loss of functional protein.