Muscular Dystrophy, Scapulohumeral
Jardine et al. (1994) described 7 affected individuals, 3 men and 4 women, in a 2-generation family segregating a scapulohumeral muscular dystrophy. Weakness began in the shoulders between 12 and 40 years of age. There was no distal weakness in the upper or lower extremities and there were no sensory abnormalities. In several cases, there was marked asymmetry with weakness on the right side more than on the left. There was no demonstrable facial weakness in any of the affected individuals. Male-to-male transmission was not observed. There was only minimal elevation of creatine kinase in some individuals. Electromyography demonstrated low amplitude, short duration, and polyphasic units. Muscle biopsy demonstrated excessive variation of muscle fiber size and scattered fibers with internal nuclei, but there was no fiber type grouping on ATPase preparations. There were no contractures or dysarthria, distinguishing this syndrome from autosomal dominant limb-girdle dystrophy (253600) which typically begins with symptoms in the lower extremities. The absence of cardiomyopathy and contractures distinguished this disorder from Emery-Dreifuss muscular dystrophy (310300; 181350). The existence of scapuloperoneal myopathy without contractures or cardiomyopathy as a separate condition from facioscapulohumeral dystrophy (FSHD; 158900) has been debated. Jardine et al. (1994) pointed out the features of their cases were similar to those of FSHD except for the absence of facial weakness. Minimally affected patients with FSHD are best detected by the presence of facial weakness. In 1 large study of FSHD, the facial weakness was absent in only 2 of 113 individuals (Lunt and Harper, 1991). In the family of Jardine et al. (1994), linkage analysis with markers D4S184, D4S139, and D4F104S1 yielded a maximum lod score of 1.61 at theta = 0.01. This suggested that the locus for scapulohumeral dystrophy may be the same as that for facioscapulohumeral dystrophy.