Objective: To determine the occurrence and the clinical and genetic variability of early-onset facioscapulohumeral muscular dystrophy (FSHD).
Design: Patients were derived from a large series of patients who participated in a genetic study of FSHD in the Netherlands.
Patients: A group of 96 patients of 17 families with autosomal dominant FSHD, nine sporadic cases of FSHD, and 35 children at risk for having the FSHD gene was searched for the presence of early-onset cases. Criteria for early-onset FSHD were (1) signs or symptoms of facial weakness before the age of 5 years and (2) signs or symptoms of shoulder girdle weakness before the age of 10 years.
Results: Six early-onset cases (four familial, two sporadic) were identified. Four of five cases showed an abnormal DNA fragment with the probe p13E-11, which has been shown to detect DNA rearrangements in FSHD patients. The clinical symptoms in these early-onset cases showed great variability with respect to rate of progression of muscle weakness, the association of hearing loss and retinopathy, and the expression of the disorder in parents and siblings.
Conclusions: Infantile FSHD has been suggested to be a separate form of the disease, often accompanied by sensorineural hearing loss and retinal telangiectasia. Our findings, as well as the fact that both hearing loss and retinal vasculopathy have been recently shown to be part of FSHD, suggest that early-onset FSHD is not a separate entity, but part of a wide clinical spectrum of FSHD.