Infantile-onset autophagic vacuolar myopathy is characterized by increased cardiac and skeletal muscle glycogen with normal acid maltase (GAA; 606800). Skeletal muscle biopsy shows characteristic intracytoplasmic vacuoles that stain for sarcolemmal proteins and complement proteins.
Similar pathologic findings are seen in Danon disease (300257), caused by mutation in the LAMP2 gene (309060) on chromosome Xq24, and X-linked myopathy with excessive autophagy (XMEA; 310440), which has been mapped to Xq28. [from
OMIM]