Infantile facioscapulohumeral muscular dystrophy: new observations.

Clinical, electrodiagnostic, and biopsy findings in a family with infantile facioscapulohumeral muscular dystrophy are reported. Four of eight family members having the disorder, all with onset in infancy, developed severe weakness leading to death in adolescence. The clinical course and prognosis of infantile facioscapulohumeral muscular dystrophy may, therefore, be as devastating as that of Duchenne muscular dystrophy. The unusual infantile presentation and high mortality in our affected family members suggest that the gene coding for this disorder may be different from that responsible for conventional facioscapulohumeral muscular dystrophy.