INCLUSION-BODY MYOSITIS IN TWINS

Sporadic inclusion body myositis (s-IBM) is characterized by late onse t of slowly progressive weakness that involves the quadriceps and vola r forearm muscles early in the course of the disease. There are heredi tary forms of inclusion body myopathy (h-IBM) that histologically rese mble s-IBM. The lack of inflammation on biopsy and the different ages at onset and patterns of muscle weakness distinguish s-IBM from h-IBM. We report twin brothers with the typical clinical and histologic feat ures of s-IBM. The occurrence of s-IBM in these twins suggests the pos sibility of a genetic susceptibility to developing s-IBM.