DiagnosisClinical DiagnosisThe clinical diagnosis of lymphedema-distichiasis syndrome is based on the presence of the following:Primary lymphedema (chronic swelling of the extremities caused by an intrinsic dysfunction of the lymphatic vessels) Distichiasis (aberrant, extra eyelashes arising from the meibomian glands) Molecular Genetic TestingGene. FOXC2 is the only gene in which mutations are known to cause lymphedema-distichiasis syndrome [Fang et al 2000]. Evidence for locus heterogeneity. Four affected families with no mutation identified in FOXC2 have been reported. Brice et al [2002] reported one out of 18 families in whom linkage was compatible with the FOXC2 locus but no mutation was identified. Finegold et al [2001] reported three small families out of 14 with no identifiable mutation; however, no linkage data were available. A duplication of a region 5’ to FOXC2 has been shown in an isolated case with lymphedema distichiasis and no FOXC2 mutation [Witte et al 2009]. It is not known if the duplication has a causative effect. Clinical testing Table 1. Summary Molecular Genetic Testing Used in Lymphedema-Distichiasis SyndromeView in own windowGene SymbolTest MethodMutations DetectedMutation Detection Frequency by Gene and Test Method ^{1Test AvailabilityFOXC2Sequence analysis Sequence variants 2~95% Clinical Deletion / duplication analysis 3Exonic or whole-gene deletions / duplicationsUnknown; none reported 41. The ability of the test method used to detect a mutation that is present in the indicated gene2. 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. No deletions or duplications involving FOXC2 have been reported to cause lymphedema-distichiasis syndrome. (Note: By definition, deletion/duplication analysis identifies rearrangements that are not identifiable by sequence analysis of genomic DNA.)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 StrategyTo confirm/establish the diagnosis in a proband Physical examination for the cardinal findings of lymphedema and distichiasis Molecular genetic testing of FOXC2 Prenatal diagnosis for at-risk pregnancies requires prior identification of the disease-causing mutation in the family. Genetically Related (Allelic) DisordersNo other phenotypes are known to be associated with FOXC2 mutations. However, a recent twin study suggested a link between FOXC2 and early onset of varicose veins [Ng et al 2005].}

Natural HistoryThe most common findings in lymphedema-distichiasis syndrome are lower-limb lymphedema and distichiasis. Lymphedema is present in most individuals with lymphedema-distichiasis syndrome. It typically appears in late childhood or puberty (age range: 7-40 years) [Erickson et al 2001, Brice et al 2002], although congenital onset has been reported [Finegold et al 2001; Brice, unpublished observations]. Lymphedema is confined to the lower limbs, is often asymmetric, and can be unilateral. The severity of the lymphedema varies within families. Males develop edema at a significantly earlier age and have more problems with cellulitis than females. Sixty-five percent of males in one series complained of recurrent cellulitis in the edematous leg, compared to 25% of females [Brice et al 2002].Primary lymphedema is usually associated with hypoplasia or aplasia of the lymphatic vessels. However, individuals with lymphedema-distichiasis syndrome have an increased number of lymphatic vessels and inguinal lymph nodes [Dale 1987, Brice 2003]. Although present, the lymphatic vessels do not appear to function properly. Isotope lymphoscintigraphy can be used to demonstrate that the swelling is caused by lymphedema. Radioactive colloid is injected into the toe web spaces and uptake in the ilioinguinal nodes is measured at intervals. Low uptake can be demonstrated in most affected individuals in association with dermal backflow, indicating lymph reflux into the lower limbs. This technique replaces lymphangiography (x-ray after injection of dye into the lymphatic vessels in the foot).Distichiasis describes the presence of aberrant eyelashes arising from the meibomian glands on the inner aspects of the inferior and superior eyelids. These range from a full set of extra eyelashes to a single hair. Distichiasis is observed in 94% of individuals with lymphedema-distichiasis syndrome [Brice et al 2002]. Although distichiasis may be present at birth, it may not be recognized until early childhood. About 75% of affected individuals have ocular problems related to distichiasis including corneal irritation, recurrent conjunctivitis, and photophobia. About 25% of individuals have no symptoms from distichiasis and are thus not aware of it. Therefore, any individual with primary lymphedema of the lower limbs should be examined carefully for the presence of distichiasis. Finegold et al [2001] described one family with a FOXC2 mutation with lymphedema only; however, only three individuals were affected and it is not known whether they were examined by slit lamp for evidence of distichiasis, which can sometimes be very subtle. In a study of 23 probands reported to have Meige disease (see Differential Diagnosis) only one was found to have a mutation in FOXC2. More extensive examination of the individuals in this family revealed that although the proband did not have distichiasis, four affected relatives had evidence of distichiasis on slit-lamp examination [Rezaie et al 2008]. In one family, distichiasis was associated with a mutation in FOXC2 but none of the affected individuals had evidence of lymphedema. The two affected individuals in the family were the 13-year-old proband (who could still develop lymphedema at a later date) and her father [Brooks et al 2003]. Varicose veins. The incidence of varicose veins is much higher (and onset earlier) in individuals with lymphedema-distichiasis syndrome than in the general population. About 50% of individuals with lymphedema-distichiasis syndrome have clinically evident varicose veins [Brice et al 2002]. In one family, light-reflective rheography and Doppler studies showed bilateral incompetence at the sapheno-femoral junction and long saphenous vein, which were presumed to be congenital abnormalities affecting both deep and superficial veins [Rosbotham et al 2000]. Ongoing studies of venous abnormalities suggest that they are present in all individuals with FOXC2 mutations [Mellor et al 2007]. Ptosis. Approximately 30% of individuals with lymphedema-distichiasis syndrome have unilateral or bilateral congenital ptosis of variable severity. Congenital heart disease occurs in 7% of individuals with lymphedema-distichiasis syndrome. Structural abnormalities include ventricular septal defect, atrial septal defect, patent ductus arteriosis, and tetralogy of Fallot. Cardiac arrhythmia, most commonly sinus bradycardia, may also occur. Cleft palate. About 4% of individuals have cleft palate with or without Pierre-Robin sequence. Other findings. Other abnormalities include scoliosis, spinal extradural cysts [Kanaan et al 2006], neck webbing, uterine and renal anomalies, strabismus, and synophrys. Neonatal chylothorax has been reported in one case in association with congenital heart disease [Chen et al 1996]. One paper suggested an association with yellow nails, but discolored nails are a common feature of chronic lymphedema regardless of cause.

Genotype-Phenotype CorrelationsNo genotype-phenotype correlation for the major clinical signs has been reported; however, a preliminary study suggested that asymptomatic anomalies of the anterior chamber of the eye are more extensive if the mutation is in the forkhead domain rather than in other regions of the gene [Lehmann et al 2003].

Differential DiagnosisLymphedema. The presence of lymphatic vessels in lymphedema-distichiasis syndrome contrasts with other causes of primary lymphedema including Milroy disease and Meige disease, which show aplasia or hypoplasia of the lymphatic vessels. In Milroy disease, lymphedema is usually present at birth and very rarely presents later. Distichiasis is not present. Milroy disease results from mutations in FLT4 (VEGFR3), encoding vascular endothelial growth factor receptor 3 [Irrthum et al 2000, Karkkainen et al 2000]. Inheritance is autosomal dominant. Meige disease presents with primary lymphedema at puberty. Distichiasis is not observed. Meige disease predominantly affects women; inheritance is autosomal dominant. The gene(s) in which mutation is causative have not yet been confirmed.Hypotrichosis-lymphedema-telangiectasia syndrome is the association of childhood-onset lymphedema in the lower limbs, loss of hair, and telangiectasia, particularly in the palms. Inheritance is either autosomal dominant or autosomal recessive. Mutations in SOX18 are causative [Irrthum et al 2003]. Lymphedema microcephaly is the association of congenital onset lymphedema with the presence of a small head circumference. Mutations in KIF11 have been found to be responsible for some cases of this condition [Ostergaard et al 2012]. Lymphedema with yellow nails (yellow nail syndrome, YNS) often presents after age 50 years. The nails in YNS are very slow growing, with transverse over-curvature and hardening of the nail plate. The nail changes are different from the typically discolored nails that are often associated with chronic lymphedema. Inheritance is said to be autosomal dominant; however, most cases are simplex (i.e., a single occurrence in a family) [Hoque et al 2007]. Emberger syndrome is the association of lower limb and genital lymphedema with myelodysplasia. Mutations in the transcription factor gene GATA2 are responsible for a proportion of cases [Ostergaard et al 2011].Distichiasis Blepharocheilodontic syndrome is the association of lagophthalmos (inability to fully close eyes), cleft lip and palate, atrial septal defect, and oligodontia. Distichiasis is a feature; lymphedema is not observed. Only one family has been reported with isolated distichiasis (i.e., absence of other malformations and/or lymphedema) [Brooks et al 2003]. Familial distichiasis has been described [OMIM 126300], but may not represent a separate genetic disorder. Others have noted individuals with "distichiasis only" in the context of a family in which both lymphedema and distichiasis were present [Falls & Kertesz 1964]. Distichiasis should also be clinically distinguished from trichiasis, a more common condition in which lashes arise normally from the anterior lamella of the eyelids but are misdirected. The misdirected lashes can cause symptoms similar to distichiasis (e.g., corneal irritation and photophobia). 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 DiagnosisTo establish the extent of disease in an individual diagnosed with lymphedema-distichiasis syndrome, the following evaluations are recommended:Referral to an ophthalmologist (preferably one familiar with distichiasis) for slit-lamp examination, as the extra lashes may be subtle and easily missed on clinical examination Physical examination to document the presence of manifestations and identify evidence of cellulitis Isotope lymphoscintigraphy to confirm underlying abnormality of the lymphatics as the cause of the edema Physical examination of the heart and possible echocardiography if murmur or arrhythmia is identified Medical genetics consultationTreatment of ManifestationsThe following are appropriate:Conservative management of symptomatic distichiasis with lubrication or epilation (plucking), or more definitive management with cryotherapy, electrolysis, or lid splitting [O'Donnell & Collin 1993]. Recurrence is possible even with more definitive treatment. Referral to a lymphedema therapist for management of edema (fitting hosiery, massage). Although the edema cannot be cured, some improvement may be possible with the use of carefully fitted hosiery and/or bandaging, which may reduce the size of the swelling as well as the discomfort associated with it. Surgery for ptosis if clinically indicated (e.g., obscured vision, cosmetic appearance) Referral to neurosurgery for individuals with symptomatic spinal cysts (i.e., any neurologic signs or symptoms especially in the lower limbs) Conservative management of varicose veins if possible, as surgery could aggravate the edema and increase the risk of infection or cellulitis Standard treatment for scoliosis Prevention of Primary ManifestationsThe implementation of hosiery prior to the development of lymphedema may be beneficial in reducing the extent of edema [P Mortimer, personal communication].Prevention of Secondary ComplicationsThe following are appropriate:Prevention of secondary cellulitis in areas with lymphedema, particularly as cellulitis may aggravate the degree of edema. Prophylactic antibiotics (e.g., penicillin V 500 mg daily) are recommended for recurrent cellulitis. Prompt treatment of early cellulitis with appropriate antibiotics (See the British Lymphology Society Consensus Statement for information on appropriate antibiotics.) It may be necessary to give the first few doses intravenously if there is severe systemic upset. Prevention of foot infections, particularly athlete's foot/infected eczema by treatment with appropriate creams/ointments Evaluation of Relatives at RiskSee Genetic Counseling for issues related to testing of at-risk relatives for genetic counseling purposes.Pregnancy Management Edema may be exacerbated during pregnancy. 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.OtherDiuretics are not effective in the treatment of lymphedema. Cosmetic surgery is often associated with disappointing results.

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. Lymphedema-Distichiasis Syndrome: Genes and DatabasesView in own windowGene SymbolChromosomal LocusProtein NameLocus SpecificHGMDFOXC216q24​.1Forkhead box protein C2FOXC2 homepage - Mendelian genesFOXC2Data 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 Lymphedema-Distichiasis Syndrome (View All in OMIM) View in own window 153400LYMPHEDEMA-DISTICHIASIS SYNDROME 602402FORKHEAD BOX C2; FOXC2Normal allelic variants. FOXC2 (NM_005251.2) comprises a single 1.5-kb exon. Normal allelic variants reported in the 5' region of the gene include -512C>T [Ridderstrale et al 2002] and -350G>T [Osawa et al 2003], and in the 3' region, 1548C>T and 1702C>T [Kovacs et al 2003]. 1761G>A has been identified [Sholto-Douglas-Vernon et al 2005]. Pathologic allelic variants. Information on at least 35 different insertions and deletions situated throughout the gene has been published to date. Over 90% of mutations are small deletions or insertions. No whole-gene deletions have been reported.The region 900-920 bp appears to be a "hot spot" for mutations, possibly because of the presence of a repeated GCCGCCGC element [Jeffery, unpublished data]. Several nonsense mutations have been reported, as well as four missense mutations: p.Ser125Leu [Bell et al 2001], p.Arg121His [Brice et al 2002], p.Trp116Arg, and p.Ser235Ile [Sholto-Douglas-Vernon et al 2005]. The first three are presumed to be disease-causing; the status of p.Ser235Ile is unknown. Table 2. FOXC2 Pathologic Allelic Variants Discussed in This GeneReviewView in own windowDNA Nucleotide ChangeProtein Amino Acid ChangeReference Sequencesc.346T>Ap.Trp116ArgNM_005251​.2
NP_005242​.1c.362G>Ap.Arg121Hisc.374C>Tp.Ser125Leuc.704G>Tp.Ser235IleSee Quick Reference for an explanation of nomenclature. GeneReviews follows the standard naming conventions of the Human Genome Variation Society (www​.hgvs.org). Note: FOXC2 mutations analogous to p.Ser125Leu and p.Arg121His inactivate FOXC1 [Saleem et al 2003]. Mutations in FOXC1 give rise to Axenfeld-Rieger anomaly and congenital glaucoma.A recent report has suggested that missense changes outside the forkhead domain can produce increased transactivational activity, which appears to be associated with a hypoplastic pattern on lymphoscintigraphy. None of the four patients with such mutations had distichiasis. [Van Steensel et al 2009].Normal gene product. Because the gene has no introns, no isomers exist. The normal product is active as a transcriptional regulator during embryonic development and is also expressed in white adipose tissue in adults and in human adult lymphatics [Petrova et al 2004]. Abnormal gene product. The assumed mechanism of pathogenesis is haploinsufficiency. It is not clear whether the frameshift mutations produce a protein product with novel amino acids or whether the mRNA or proteins are degraded.