Facioscapulohumeral muscular dystrophy

A decade's progress in facioscapulohumeral muscular dystrophy genetics has been marked by the discovery of novel genetic phenomena such as crossover o f subtelomeric DNA between chromosomes 4 and 10 in normal individuals and b y the recognition that the facioscapulohumeral muscular dystrophy deletion- mutation may cause a position variegation effect on more proximal DNA. The mutated DNA itself is probably not transcribed. Larger deletions tend to ca use more severe disease. Antenatal diagnosis, based on detection of the sho rt fragment of mutated DNA, is possible in between 95 and 100% of cases, de pending on the precise nature of the parental facioscapulohumeral muscular dystrophy mutation. Yet remarkably, the nature of the gene product(s) of th e affected proximal gene(s), as well as of the molecular pathogenesis of fa cioscapulohumeral muscular dystrophy muscle, retinal and cochlear disease, is completely unknown. Marked perivascular inflammation is often present in facioscapulohumeral muscular dystrophy muscle biopsies. The expression of facioscapulohumeral muscular dystrophy within reported monozygotic twinship s differs greatly. This raises the question of whether variations in expres sion of the T-cell receptor gene repertoire or of other immune genes play a n important modifying role in determining the severity of facioscapulohumer al muscular dystrophy. A focus on traditional scientific disciplines may no w be appropriate. Symptomatic treatments, for instance of scapular winging and of lagophthalmos, are important, and timely photocoagulation of the ret inal exudates which are a very rare, but real, complication of retinal tela ngiectasis can curtail visual loss. The results of collobarative trials of pharmacological agents such as albuterol which affect muscle mass and devel opment are awaited. Curr Opin Neurol 12:501-511. (C) 1999 Lippincott Willia ms & Wilkins.