X-linked myopathy with postural muscle atrophy

X-linked myopathy with postural muscle atrophy (also known as X-linked myopathy with excessive autophagy, or XMEA) is a rare inherited muscle disorder that primarily affects males. It is caused by mutations in the VMA21 gene on the X chromosome, which encodes a protein involved in the assembly of the vacuolar ATPase proton pump. This defect leads to excessive autophagy (a cellular self-digestion process) within muscle fibers, resulting in progressive muscle weakness and wasting. The disease predominantly affects postural muscles, particularly those of the legs and trunk, leading to difficulty with walking, climbing stairs, and maintaining posture. Onset typically occurs in childhood or adolescence, though the rate of progression can vary. Affected individuals may develop progressive proximal muscle weakness, with the lower limbs often more severely involved than the upper limbs. Muscle biopsy characteristically shows autophagic vacuoles with sarcolemmal features (AVSF) and complement C5b-9 deposits on the vacuolar membranes. Serum creatine kinase levels may be mildly to moderately elevated. There is currently no specific cure or disease-modifying treatment for X-linked myopathy with postural muscle atrophy. Management is supportive and symptomatic, including physical therapy to maintain mobility and function, orthopedic interventions as needed, and monitoring for respiratory complications in advanced cases. Genetic counseling is recommended for affected families, as carrier females are generally asymptomatic or mildly affected.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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