Determination of Contraction of D4Z4 Repeats on Chromosome 4q35 in Iranian Facioscapulohumeral Muscular Dystrophy Patients

Facioscapulohumeral Muscular Dystrophy (FSHD)is characterized by weakness of the facial, scapular muscles and the dorsiflexors of the foot. Severity in this disorder is highly variable. Approximately 95% of individuals with FSHD phenotype have type 1 FSHD, with D4Z4 allele of between one and ten repeat units and about 5% have type 2 FSHD with mutations in the chromatin modifier SMCHD1gene which causes the chromatin relaxation at D4Z4. We studied 49 Iranian patients with clinical findings of FSHD, and detected contraction of the D4Z4 repeats located at 4q35 in 40, confirming FSHD type I in 40.