Atypical phenotypes in patients with facioscapulohumeral muscular dystrophy 4q35 deletion

Background: Facioscapulohumeral muscular dystrophy (FSHD) is associated with a deletion on chromosome 4q35. Recent studies have shown that this deletion is found in patients with other phenotypes in addition to those with the classic Landouzy-Dejerine FSHD phenotype. Objective: To examine patients with atypical phenotypes and an FSHD deletion on chromosome 4q35. Design: Clinical characterization and genotype phenotype correlation. Setting: University hospital. Patients: Forty-one symptomatic subjects with deletions on chromosome 4q35. Results: We found 6 patients with atypical FSHD. Three (from a single family with FSHD) had additional symptoms of chronic progressive external ophthalmoplegia (4q35 EcoRI/BlnI fragment size, 20 kilobase [kb]), and 3 patients (1 with sporadic disease and 2 from a single family) had facial-sparing scapulohumeral dystrophy (4q35 EcoRI/ BlnI fragment size, 30 and 34 kb, respectively). Conclusions: The clinical presentations in patients with FSHD-associated short fragments on chromosome 4q35 are not restricted to the classic FSHD form, but constitute a variety of clinical manifestations. There seems to be no clear correlation between the atypical subtype and the DNA fragment size due to the deletion.