Facioscapulohumeral dystrophy is an autosomal dominant muscular dystrophy, the gene for which is localized to 4q35. It appears to be caused by deletion of tandem repeats that do not contain an expressed sequence. One current hypothesis is that the deletion affects expression of a centromeric gene (not yet identified) through a position effect. The mouse mutant, myodystrophy (myd), is a candidate model for facioscapulohumeral dystrophy. Myd has a progressive muscular dystrophy and maps to a segment of mouse chromosome 8 that is syntenic with human 4q31-4q35.