Characterization of antibodies to subcellular fractions of skeletal muscles in patients with Myasthenia Gravis and Autoimmune Rippling Muscle Disease, /

Abstract

Rippling muscle disease (RMD) is a rare autosomal dominant disease characterized by muscle weakness after resting, and electrically "silent" wave-like contractions of skeletal muscle activated by percussion or stretch. In 1995, Carl Ansevin M.D. diagnosed a patient with rippling muscle disease associated with myasthenia gravis (MG) (Ansevin and Agmano1is, 1996). This patient had no family history ofRMD and experienced a disappearance ofRMD symptoms after a thymectomy suggesting that RMD associated with MG may have an autoimmune origin. From western blot examination of sera from this patient and sera from other MG patients at varying severity levels (both with and without the RMD component) it was shown that MG/RMD patients displayed immunoreactivity to a skeletal muscle protein 66-97 kDa in size as well as immunoreactivity to proteins with molecular weights of200 kDa and 300-500 kDa. Western blot analysis ofMG/RMD patients' sera displayed immunoreactivity with T-tubu1ar membranes ofrat skeletal muscle. However, this same immunoreactivity was also shown in a patient without the rippling muscle component thus indicating that these antibodies may be due to the MG, not the rippling muscle component. Sarcoplasmic reticular fractions ofrat skeletal muscle did not display any immunoreactivity to MG/RMD patient sera.