DiagnosisClinical DiagnosisThe diagnosis of Wolf-Hirschhorn syndrome (WHS) is suggested by the characteristic facial appearance, growth delay, psychomotor retardation, and seizures and is confirmed by detection of a deletion of the Wolf-Hirschhorn critical region (WHCR) (chromosome 4p16.3).Typical facial features. The facial appearance of individuals with WHS changes with age, exhibiting a typical pattern at each period [Battaglia et al 2000]. Facial features include the 'Greek warrior helmet appearance' of the nose (the broad bridge of the nose continuing to the forehead) recognizable in all individuals from birth to childhood and becoming less evident at puberty. Other craniofacial features are microcephaly, high forehead with prominent glabella, ocular hypertelorism, epicanthus, highly arched eyebrows, short philtrum, downturned mouth, micrognathia, and poorly formed ears with pits/tags [Battaglia et al 1999a, Battaglia et al 1999b, Battaglia et al 2000, Battaglia & Carey 2000, Battaglia et al 2008]. Prenatal-onset growth deficiency is followed by postnatal growth retardation in all affected individuals. Developmental delay/intellectual disability of variable degree is present in all. Hypotonia and muscle underdevelopment, mainly of the lower limbs, is observed in all affected individuals. TestingCytogenetic analysis. Conventional G-banded cytogenetic studies detect a deletion in the distal portion of the short arm of one chromosome 4 involving band 4p16.3 in approximately 50%-60% of individuals with WHS. Many individuals (~55%) have a deletion with no other cytogenetic abnormality (a so-called "pure deletion"). However, G-banded cytogenetic studies or FISH alone may not reveal other complex genomic alterations that help determine the type of rearrangement leading to the 4p16.3 deletion. About 40%-45% of affected individuals have an unbalanced translocation with both a deletion of 4p and a partial trisomy of a different chromosome arm. These unbalanced translocations may be de novo or inherited from a parent with a balanced rearrangement. The remaining individuals have other complex rearrangements leading to a 4p16.3 deletion (e.g., ring 4) [South et al 2008a]. Molecular Genetic TestingGene. Deletion of the Wolf-Hirschhorn syndrome critical region (within 4p16.3 at ~1.4-1.9 Mb from the terminus) is the only known cause of Wolf-Hirschhorn syndrome. Clinical testingDeletion/duplication analysis detects changes in copy number of a region or across the genome:FISH (fluorescence in situ hybridization). FISH using a WHSCR probe detects more than 95% of deletions in WHS. However, G-banded cytogenetic studies or FISH alone may not reveal other complex genomic alterations that help determine the type of rearrangement leading to the 4p16.3 deletion. Chromosomal microarray (CMA) technology as well as FISH and/or G-banded cytogenetic studies may be necessary for complete characterization of the chromosome rearrangement associated with the 4p16.3 deletion [South et al 2008a]. Note: Probe localization is important as a probe that falls outside of the WHSCR may give a false negative result. If a subtelomeric probe kit is used, interstitial deletions may not be detected. Deletion/duplication analysis targeted to 4p16.3. A variety of methods can target the region spanning the WHSCR to detect and define the extent of the deletion.Deletion/duplication analysis by chromosomal microarray (CMA). Genome-wide CMA (e.g., aCGH) can detect the deletion, extent of the deletion, unbalanced translocations, and other complex arrangements. A combination of CMA, FISH, and/or G-banded cytogenetic studies may be necessary for complete characterization of the chromosome rearrangement. Table 1. Summary of Testing Used in Wolf-Hirschhorn SyndromeView in own windowTest Type Rearrangement Detected Mutation Detection Frequency by Test Type ^{1Test AvailabilityCytogenetic analysis Deletion or other complex rearrangements leading to deletion of 4p16.3~50%-60%ClinicalDeletion/
duplication
analysis 2 FISHDeletion of WHSCR in 4p16.3 >95% Clinical Targeted to 4p16.3Deletion of WHSCR in 4p16.3>95%Chromosomal microarray analysisExtent of deletion of 4p16.3 or other complex rearrangements leading to deletion of 4p16.3>95%Clinical 1. The ability of the test method used to detect a mutation that is present in the indicated gene2. Testing that identifies deletions/duplications not readily detectable by sequence analysis of genomic DNA; a variety of methods including quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), or targeted chromosomal microarray analysis (gene/segment-specific) may be used. A full chromosomal microarray analysis that detects deletions/duplications across the genome may also include this gene/segment.Testing Strategy To confirm/establish the diagnosis in a probandConventional cytogenetic studies to detect large deletions and more complex cytogenetic rearrangements (ring chromosome, unbalanced chromosome translocations)FISH analysis to detect smaller deletions involving the WHSCR. Genome-wide CMA to detect deletions involving the WHSCR or imbalances resulting from more complex rearrangements associated with the 4p16.3 deletion as demonstrated by unbalanced translocationsPrenatal diagnosis and preimplantation genetic diagnosis (PGD) for at-risk pregnancies require prior identification of a balanced translocation in one parent. Genetically Related (Allelic) DisordersNo phenotypes other than those discussed in this GeneReview are associated with deletion of the WHSCR in 4p16.3.}

Natural HistoryAlthough previously thought to be separate disorders, Wolf-Hirschhorn syndrome (WHS) and Pitt-Rogers-Danks syndrome (PRDS) are now recognized as forms of the same syndrome [Battaglia et al 2001]. PRDS was described in 1984 in four individuals (two of whom are sisters) with intrauterine growth retardation, short stature, microcephaly, a characteristic face, intellectual disability, and seizures. Twelve years later, Clemens et al [1996] described a distal 4p microdeletion identical to that seen in individuals with WHS in two previously unreported individuals, as well as in the siblings in the original report. The similarity in the size of the WHS and PRDS critical regions in combination with the phenotypic similarities of these syndromes suggests that PRDS and WHS represent the clinical spectrum associated with a single syndrome. Classic WHS. Table 2 summarizes the frequency of clinical findings associated with WHS. Table 2. Frequency of Clinical Findings in Wolf-Hirschhorn SyndromeView in own windowFindingsFrequencyDistinctive facial features (see Clinical Diagnosis)
IUGR/postnatal growth retardation
Intellectual disability
Hypotonia
Decreased muscle bulk
Seizures and/or distinctive EEG abnormalities
Feeding difficulties >75%Skin changes (hemangioma; marble/dry skin)
Skeletal anomalies
Craniofacial asymmetry
Ptosis
Abnormal teeth
Antibody deficiency 50%-75%Hearing defects
Heart defects
Eye/optic nerve defects
Cleft lip/palate
Genitourinary tract defects
Structural brain anomalies
Stereotypies (hand washing/flapping, rocking) 25%-50%Anomalies of the following:
 • Liver
 • Gallbladder
 • Gut
 • Diaphragm
 • Esophagus
 • Lung
 • Aorta <25%From Battaglia & Carey [2000], Battaglia et al [2001], Battaglia et al [2008]Postnatal growth retardation. Most individuals with WHS have marked intrauterine growth retardation, short stature, and slow weight gain later in life despite adequate energy and protein intake [Battaglia et al 1999a, Battaglia et al 1999b, Battaglia & Carey 2000, Battaglia et al 2008]. Specific growth charts have recently been produced for children from birth to age four years [Antonius et al 2008]. In all affected individuals, except those with certain cryptic unbalanced translocations, head circumference is less than the second centile [South et al 2008c]. Intellectual disability. Although it is commonly stated that individuals with WHS have severe/profound intellectual disability do not develop speech, and have minimal communication skills, recent experience has identified a broader range of intellectual abilities in individuals with WHS. Battaglia et al [2008] found that the degree of intellectual disability was mild in 10%, moderate in 25%, and severe/profound in 65%. Thus, one third of affected individuals had mild to moderate disability. Expressive language, although limited to guttural or disyllabic sounds in most individuals, was at the level of simple sentences in 6%. Comprehension seems to be limited to a specific context. Intent to communicate appears to be present in most individuals with WHS and improves over time with extension of the gesture repertoire. In a recent preliminary study, Fisch et al [2008] observed relative strengths in verbal and quantitative reasoning, while adaptive behavior profiles noted relative strengths in the socialization domain.About 10% of affected individuals do achieve sphincter control by day, usually between ages eight and 14 years. By age two to 12 years, approximately 45% of affected individuals walk, either independently (25%) or with support (20%) [Battaglia & Carey 2000, Battaglia et al 2008]. About 30% of children reach some autonomy with eating (10% self-feed), dressing and undressing (20%), and simple household tasks. Slow but constant improvement has been observed over time in all individuals with WHS; these individuals reach more advanced milestones than previously suggested. Seizures occur in 50%-100% of children with WHS [Battaglia et al 1999a, Battaglia et al 1999b, Battaglia & Carey 2000, Battaglia et al 2009]. Age at onset varies between three and 23 months with a peak incidence around six to 12 months. Seizures are either unilateral clonic or tonic, with or without secondary generalization, or generalized tonic-clonic from the onset; they are frequently triggered by fever and can occur in clusters and last over 15 minutes. Other seizure types described in a few individuals include tonic spasms, myoclonic seizures, and complex partial seizures [Battaglia & Carey 2005]. Status epilepticus occurs in as many as 50% of individuals. Atypical absences develop between ages one and six years in one third of children [Battaglia et al 2009]. Seizures can be difficult to control in some individuals during the early years, but if properly treated tend to disappear with age. Seizures stop by age two to 13 years in up to 55% of individuals [Battaglia et al 2009]. Distinctive electroencephalographic (EEG) abnormalities have been found in 90% of individuals with WHS [Battaglia et al 2009].Feeding difficulties may be caused by hypotonia and/or oral facial clefts with related difficulty in sucking, poorly coordinated swallow with consequent aspiration, and/or gastroesophageal reflux. Gastroesophageal reflux, though transitory in healthy infants, usually persists in infants with WHS and results in failure to thrive and respiratory diseases. Skeletal anomalies found in 60%-70% of individuals with WHS [Battaglia et al 1999a, Battaglia et al 1999b, Battaglia & Carey 2000, Battaglia et al 2008] include kyphosis/scoliosis with malformed vertebral bodies, accessory or fused ribs, clubfeet, and split hand [Shanske et al 2010]. Ophthalmologic abnormalities. Exodeviation, nasolacrimal obstruction, eye or optic nerve coloboma, and foveal hypoplasia are the most common ophthalmic manifestations of WHS [Battaglia et al 2001, Wu-Chen et al 2004, Battaglia et al 2008]. Eyelid hypoplasia, requiring skin grafting, has occasionally been observed [Battaglia et al 2001]. Glaucoma can be difficult to treat. Dental abnormalities. Delayed dental eruption with persistence of deciduous teeth, taurodontism in the primary dentition, peg-shaped teeth, and agenesis of some dental elements can be seen in more than 50% of individuals [Battaglia & Carey 2000, Battaglia et al 2001, Battaglia et al 2008]. Congenital heart defects are noted in about 50% of individuals and are usually not complex. The most frequent is atrial septal defect (27%), followed by pulmonary stenosis, ventricular septal defect, patent ductus arteriosus, aortic insufficiency, and tetralogy of Fallot [Battaglia et al 1999a, Battaglia et al 1999b, Battaglia & Carey 2000, Battaglia et al 2008]. Antibody deficiencies (IgA/IgG2 subclass deficiency; isolated IgA deficiency; impaired polysaccharide responsiveness) found in 69% of children studied by Hanley-Lopez et al [1998] seem to be responsible for recurrent respiratory tract infections and otitis media. Hematopoietic dysfunction has been reported in two children with WHS; dysfunction progressed to refractory cytopenia in one and to acute lymphoblastic leukemia in the other [Sharathkumar et al 2003]. Hearing loss, mostly of the conductive type, can be detected in more than 40% of individuals with WHS. Sensorineural hearing loss has been reported in 15% of individuals [Battaglia & Carey 2000, Battaglia et al 2008]. Congenital abnormalities of the middle and inner ear appear to contribute to the hearing impairment [Ulualp et al 2004]. Urinary tract malformations can be seen in more than 30% of affected individuals and include renal agenesis, cystic dysplasia/hypoplasia, oligomeganephroma (defined as renal hypoplasia characterized by decreased numbers of nephrons and hypertrophy of all nephric elements), horseshoe kidney, renal malrotation, bladder exstrophy, and obstructive uropathy. Oligomeganephroma is associated with chronic renal failure. Some of these anomalies can be associated with vesicoureteral reflux [Battaglia & Carey 2000, Grisaru et al 2000, Battaglia et al 2008]. Hypospadias and cryptorchidism can be seen in 50% of males [Battaglia & Carey 2000].Absent uterus, streak gonads, and clitoral aplasia/hyperplasia have been reported in females [Battaglia et al 2008].Structural central nervous system defects have been reported in up to 80% of affected individuals [Battaglia et al 2008]. These defects mainly include thinning of the corpus callosum associated, in a few cases, with diffusely decreased white matter volume, enlargement of lateral ventricles, cortical/subcortical atrophy, or marked hypoplasia/agenesis of the posterior lobes of both cerebellar hemispheres. Other reported anomalies are hypoplastic brain with narrow gyri, arhinencephaly, shortening of the H2 area of Ammon's horn, and dystopic dysplastic gyri in the cerebellum [Battaglia & Carey 2000]. Sleep problems, common in early years, can be easily resolved [Battaglia et al 2001]. Other. A wide variety of congenital defects have been reported in a minority of individuals with WHS [Battaglia et al 2001].

Genotype-Phenotype CorrelationsIn order to explain the wide phenotypic variability of WHS, investigators have searched for correlations between size of the 4p deletion and severity of clinical manifestations.Although Wieczorek et al [2000], Zollino et al [2000], and Zollino et al [2008] have respectively suggested a partial or a complete genotype-phenotype correlation, some investigators have concluded that no such correlation exists [Battaglia et al 1999a, Battaglia et al 1999b]. Meloni et al [2000] observed individuals with the 'classic syndrome' with severe intellectual disability and a submicroscopic deletion detected only by FISH, as well as individuals with mild to moderate intellectual disability and no major malformations with large deletions detected by routine cytogenetic analysis. These observations suggest that the size of the deletion does not correlate with severity of the clinical findings. Some of the associated structural defects, including cleft palate and heart defects, occur more frequently in individuals who have deletions greater than 3 Mb in length [Zollino et al 2008]. The classic phenotype may include less typical defects in persons with WHS and partial trisomy of another chromosome resulting from an unbalanced translocation.Recently, it has been shown that double cryptic chromosome imbalances, initially mistaken as microdeletions, cause large deletions and can be an important factor in explaining phenotypic variability in Wolf-Hirschhorn syndrome [Zollino et al 2004]. The deletion size has a partial correlation to severity but some individuals are either more or less severely affected than would be expected by deletion size. Appropriate seizure control likely also impacts degree of impairment. Deletions from the 4p terminus larger than 22 to 25 megabases in length are associated with a severe phenotype that is said to differ from the spectrum observed in WHS [Zollino et al 2008].Deletions distal to the WHSCR may be either benign or associated with a mild developmental delay, growth delay, and possible seizures; but without the diagnostic features of WHS [South et al 2008c].

Differential DiagnosisProximal 4p deletion. Several individuals with an interstitial deletion of 4p have been described. This deletion usually involves bands 4p12-p16, which are proximal to and exclude the WHS critical region. This disorder is distinct from WHS and is a discrete syndrome [Bailey et al 2010].WHS phenotype. The clinical phenotype and particularly the facial gestalt of WHS are characteristic; however, some individuals may still be misdiagnosed because of features that overlap with the following disorders: Seckel syndrome, characterized by pre- and postnatal growth deficiency, microcephaly, beaked/prominent nose CHARGE syndrome, characterized by coloboma, heart defects, choanal atresia, retarded growth and development, genital abnormalities, and ear anomalies/deafness. CHARGE syndrome is associated with mutations in CDH7. Smith-Lemli-Opitz syndrome (SLOS), characterized by pre- and postnatal growth retardation, microcephaly, moderate to severe intellectual disability, and multiple major and minor malformations. The malformations include distinctive facial features, cardiac defects, underdeveloped external genitalia in males, postaxial polydactyly, and 2-3 syndactyly of the toes. SLOS is caused by mutation in DHCR7, resulting in deficiency of the enzyme 7-dehydrocholesterol reductase. It is an autosomal recessive disorder; diagnosis relies upon clinical suspicion and detection of elevated serum concentration of 7-dehydrocholesterol or an elevated 7-dehydrocholesterol:cholesterol ratio. Opitz G/BBB syndrome, characterized by facial anomalies (ocular hypertelorism, prominent forehead, widow's peak, broad nasal bridge, anteverted nares), laryngo-tracheo-esophageal defects, and genitourinary abnormalities (hypospadias, cryptorchidism, and hypoplastic/bifid scrotum). Developmental delay/intellectual disability and cleft lip and/or palate are present in approximately 50%. Malformations present in fewer than 50% of individuals include congenital heart defects, imperforate or ectopic anus, and midline brain defects (Dandy-Walker malformation and agenesis or hypoplasia of the corpus callosum and/or cerebellar vermis). Genetic heterogeneity has been demonstrated: an X-linked form is caused by mutations in the gene MID1 (locus Xp22.3) and an autosomal dominant form is linked to 22q11.2. Malpuech syndrome, characterized by growth retardation, ocular hypertelorism, wide forehead, high-arched eyebrows, urogenital anomalies, and hearing problems Lowry-MacLean syndrome, characterized by growth failure, intellectual disability, cleft palate, congenital heart defect, and glaucoma Williams syndrome (WS), characterized by cognitive impairment (usually mild intellectual disability), a specific cognitive profile, unique personality characteristics, distinctive facial features, and cardiovascular disease (elastin arteriopathy). A range of connective tissue abnormalities is observed and hypercalcemia and/or hypercalciuria are common. WS is caused by the contiguous gene deletion of the WS critical region (at 7q11.23) encompassing the elastin (ELN) gene. More than 99% of individuals with the clinical diagnosis of WS have this contiguous gene deletion, which can be detected using fluorescent in situ hybridization (FISH). It is transmitted in an autosomal dominant manner. Most cases are de novo occurrences. Rett syndrome, an X-linked dominant disorder that in girls is characterized by normal birth and apparently normal psychomotor development during the first six to 18 months of life followed by a short period of developmental stagnation then by rapid regression in language and motor skills. The hallmark of the disease is the loss of purposeful hand use and its replacement with repetitive stereotyped hand movements. Autistic features, panic-like attacks, bruxism, episodic apnea and/or hyperpnea, gait ataxia and apraxia, tremors, and acquired microcephaly also occur. The disease becomes relatively stable, but girls will likely develop dystonia and foot and hand deformities as they grow older. Seizures occur in 50% of females with Rett syndrome; generalized tonic-clonic seizures and partial complex seizures are the most common. The incidence of sudden, unexplained death is increased. Males with a 46,XY karyotype may have such a severe neonatal encephalopathy that they die before their second year. The diagnosis rests on clinical diagnostic criteria established for the classic syndrome and/or molecular testing of the MECP2 gene.Angelman syndrome (AS), characterized by severe developmental delay/intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs, and a unique behavior with an inappropriate happy demeanor that includes frequent laughing, smiling, and excitability. Microcephaly and seizures are common. The diagnosis rests on a combination of clinical features and molecular genetic testing and/or cytogenetic analysis. Consensus clinical diagnostic criteria for AS have been developed. Analysis of parent-specific DNA methylation imprints in the 15q11.2-q13 chromosome region detects approximately 78% of individuals with AS, including those with a deletion, uniparental disomy, or an imprinting defect; fewer than 1% of individuals have a cytogenetically visible chromosome rearrangement (i.e., translocation or inversion). UBE3A sequence analysis detects mutations in an additional approximately 11% of individuals. Accordingly, molecular genetic testing (methylation analysis and UBE3A sequence analysis) identifies alterations in about 90% of individuals. The remaining 10% of individuals with classic phenotypic features of AS are affected as the result of a presently unidentified genetic mechanism and thus are not amenable to diagnostic testing. Smith-Magenis syndrome (SMS), characterized by distinctive facial features, developmental delay, cognitive impairment, and behavioral abnormalities. The facial appearance is characterized by a broad square-shaped face, brachycephaly, prominent forehead, synophrys, upslanting palpebral fissures, deep-set eyes, broad nasal bridge, marked midfacial hypoplasia, short, full-tipped nose with reduced nasal height, micrognathia in infancy changing to relative prognathia with age, and a distinct appearance of the mouth, with fleshy everted upper lip with a "tented" appearance. Cognitive and adaptive abilities are usually in the moderate range of intellectual disability. The behavioral phenotype includes significant sleep disturbance, stereotypies, and maladaptive and self-injurious behaviors. Infancy is characterized by feeding difficulties, failure to thrive, hypotonia, prolonged napping or need to awaken for feeds, and generalized lethargy. SMS is caused by an interstitial deletion of the short arm of chromosome 17 band p11.2 (del17p11.2) detectable by G-banded cytogenetic analysis and/or by fluorescence in situ hydridization (FISH). A visible interstitial deletion of chromosome 17p11.2 can be detected in all individuals with the common deletion by a routine G-banded analysis provided the resolution is adequate (550 band or higher). Molecular genetic testing of RAI1, the gene in which mutation is causative, is possible for individuals in whom a FISH-detectable deletion has been excluded. 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).

ManagementEvaluations Following Initial Diagnosis To establish the extent of disease in an individual diagnosed with Wolf-Hirschhorn syndrome, the following evaluations are recommended:Measurement of growth parameters and plotting on growth charts Physical and neurologic examination Evaluation of cognitive, language, and motor development and social skills Waking/sleeping video-EEG-polygraphic studies in childhood (mainly ages 1-6 years) to detect atypical absence seizures that may be subtle [Battaglia & Carey 2000, Battaglia et al 2009] Evaluation for feeding problems and gastroesophageal reflux with referral to a dysphagia team Physical examination for skeletal anomalies (e.g., club foot, scoliosis, kyphosis); if anomalies are present, referral for orthopedic and physical therapy evaluation (including full biomechanical assessment) Ophthalmology consultation in infancy even in the absence of overt anomalies Examination of the heart (auscultation, electrocardiogram, echocardiography) in infancy Testing for immunodeficiency (particularly plasma Ig levels, lymphocyte subsets, and polysaccharide responsiveness); although limited data on immunodeficiency in individuals with WHS are available, such testing should be considered when clinically appropriate. Comprehensive evaluation by an otolaryngologist and comprehensive audiologic screening (brain stem auditory evoked responses) as early as possible to allow appropriate interventions Renal function testing annually and renal ultrasonography in infancy to detect structural renal anomalies and/or vesicoureteral reflux [Grisaru et al 2000] Treatment of ManifestationsIntellectual disability. Enrollment in a personalized rehabilitation program with attention to motor development, cognition, communication, and social skills is appropriate [Battaglia & Carey 2000, Battaglia et al 2008]. Use of sign language enhances communication skills and does not inhibit the appearance of speech. Early intervention and, later, appropriate school placement are essential. Seizures. Because almost 95% of individuals with Wolf-Hirschhorn syndrome have multiple seizures, most often triggered by fever, and almost one third later develop valproic acid-responsive atypical absences, it is appropriate to start treatment with valproic acid soon after the first seizure. Atypical absences are well controlled on valproic acid alone or in association with ethosuccimide [Battaglia & Carey 2000, Battaglia et al 2009].Sodium bromide has recently been proposed as the initial treatment for the prevention of the development of status epilepticus [Kagitani-Shimono et al 2005]. Clonic, tonic-clonic, absence, or myoclonic status epilepticus can be well controlled by intravenous benzodiazepines (Diazepam) [Battaglia & Carey 2005, Kagitani-Shimono et al 2005]. Because individuals with WHS have distinctive electroencephalographic (EEG) abnormalities not necessarily associated with seizures [Battaglia et al 2009]. It seems appropriate to withdraw antiepileptic drugs in individuals who have not experienced seizures for five years.Feeding difficulties. Feeding therapy with attention to oral motor skills is also appropriate. Special feeding techniques or devices such as the "Haberman feeder" can be used for feeding a hypotonic infant/child without a cleft palate or those with a cleft palate prior to surgical repair. Gavage feeding in individuals with poorly coordinated swallow.Gastroesophageal reflux should be addressed in a standard manner.In one study, almost 44% of individuals with WHS were managed with gastrostomy and, occasionally, gastroesophageal fundoplication [Battaglia & Carey 2000]. Skeletal abnormalities (e.g., clubfoot, scoliosis, kyphosis) need to be addressed on an individual basis. Early treatment (both physical therapy and surgery) is suggested. Ophthalmologic abnormalities are treated in the standard manner. Congenital heart defects are usually not complex and are amenable to repair. Hearing loss is treated with a trial of hearing aids. Sleeping problems. If no medical factors (e.g., otitis media, gastroesophageal reflux, eczema) are involved and if sleeping problems are reinforced by parental attention, the 'extinction of parental attention' is an effective behavioral treatment [Curfs et al 1999]. Other structural anomalies (e.g., diaphragmatic, gastrointestinal, dental) should be addressed in a standard manner. Prevention of Secondary ComplicationsAntibiotic prophylaxis is indicated for vesicoureteral reflux.Intravenous Ig infusions or continuous antibiotics may be indicated for those with antibody deficiencies. SurveillanceSystematic follow-up allows for adjustment of rehabilitation and treatment as skills improve or deteriorate and medical needs change [Ferrarini et al 2003, Battaglia et al 2008, Battaglia 2010].Evaluation of Relatives at RiskSee Genetic Counseling for issues related to testing of at-risk relatives for genetic counseling purposes.Therapies Under InvestigationSearch ClinicalTrials.gov for access to information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.OtherCarbamazepine may worsen the electroclinical picture in individuals with atypical absence seizures [Battaglia & Carey 2005].

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. Wolf-Hirschhorn Syndrome: Genes and DatabasesView in own windowCritical RegionGene SymbolChromosomal LocusProtein NameWHCRUnknown4p16​.3UnknownData 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 Wolf-Hirschhorn Syndrome (View All in OMIM) View in own window 194190WOLF-HIRSCHHORN SYNDROME; WHS 602952WHS CANDIDATE 1 GENE; WHSC1Molecular Genetic PathogenesisThe proximal boundary of the WHSCR was defined by the identification of two individuals with the WHS phenotype and a 1.9-Mb terminal deletion of 4p16.3 that includes the candidate genes LEMT1 and WHSC1 [Zollino et al 2003, Rodriguez et al 2005]. The distal boundary of the WHSCR was established through the analysis of persons with an interstitial 4p16 deletion and a WHS phenotype [Wright et al 1997] and persons with a terminal 4p deletion without a WHS phenotype [South et al 2008c].In 85% of de novo deletions, the origin of the deleted chromosome is paternal.WHSC1 is a novel gene that spans a 90-kb genomic region, two thirds of which maps in the telomeric end of the WHCR. The temporal and spatial expression of WHSC1 in early development and the protein domain identities suggest that WHSC1 may play a significant role in normal development. Its deletion is likely to contribute to the WHS phenotype. However, the variation in severity and phenotype of WHS suggests possible roles for genes that lie proximally and distally to the WHSCR, including WHSC2 and LETM1 [Zollino et al 2003, Bergemann et al 2005, Rodriguez et al 2005, South et al 2007].LETM1 has been proposed as a candidate gene for the seizures. Its position immediately distal to the critical region means that it is deleted in almost all affected individuals. In yeast, it has been shown to be involved in mitochondrial potassium homeostasis [Nowikovsky et al 2004, Schlickum et al 2004]. It is also possible that LETM1 is not the only gene involved in the occurrence of seizures, as seizures have been observed in individuals with deletions that do not include this gene [Maas et al 2008]Much work is still needed to identify the function of WHSC1 and LETM1 in individuals with normal development and in individuals with WHS, and to characterize any additional genes in and around the WHSCR. As detailed analysis of the breakpoints of deletions becomes available, it may become easier to correlate genotype with phenotype for small deletions, possibly elucidating the role that genes outside the WHSCR play in WHS. This understanding may be furthered by the generation of a mouse model for WHS in which deletions of varying sizes span the WHSCR syntenic region. The phenotype of these animals was variable but included midline, craniofacial, and ocular defects as well as seizures [Naf et al 2001, Simon & Bergemann 2008].The fibroblast growth factor receptor-like 1 (FGFRL1) gene, located at 4p16.3, represents a plausible candidate gene for part of the craniofacial phenotype of WHS [Engbers et al 2009]. FGFRL1 is involved in bone and cartilage formation during embryonic development and the Fgfrl1 null mice has been shown to recapitulate several multiple congenital malformations of WHS [Catela et al 2009].