DISTAL MYOPATHY WITH RIMMED VACUOLES

Distal myopathy with rimmed vacuoles is an autosomal recessively inher ited disorder with preferential involvement of the anterior tibial mus cle. Recently the gene was discovered to be mapped to chromosome 9, th e same region as in familial inclusion body myopathy trimmed vacuole m yopathy sparing the quadriceps). The onset of the disease was in young adults 20-40 years of age, averaging 26 years. The disease was progre ssive and most of the patients became non-ambulant within 12 years aft er the onset. The striking and common pathologic finding was the prese nce of rimmed vacuoles in muscle fibers with little evidence of necrot ic or regenerative processes. Nuclear change with tubulofilamentous in clusions probably induces focal myofibrillar degeneration which activa tes the lysosomal system, resulting in active autophagocytosis and mye lin body formation, i.e. rimmed vacuole formation. (C) 1998 Elsevier S cience B.V. All rights reserved.