PrP accumulation has been observed in the skeletal muscles of patients with inclusion-body myositis, polymyositis, dermatomyositis, and neurogenic muscle atrophy, and we have previously reported that over-expression of wild type PrP in the skeletal muscles is sufficient to cause myopathy in the Tg(HQK) mice [[7] and references therein], which suggest that muscular accumulation of PrP may contribute to the pathogenesis of some human muscle diseases. The gene discussed is PRNP; the disease is polymyositis.