X-linked centronuclear myopathy

X-linked centronuclear myopathy (XLCNM), also known as X-linked myotubular myopathy (XLMTM), is a severe congenital muscle disorder caused by mutations in the MTM1 gene located on the X chromosome. This gene encodes myotubularin, a phosphoinositide phosphatase essential for normal muscle cell development and maintenance. Because of its X-linked recessive inheritance, the condition predominantly affects males, while female carriers are usually unaffected or mildly affected. The disease is characterized by profound skeletal muscle weakness and hypotonia present at birth, often accompanied by respiratory insufficiency requiring mechanical ventilation. The hallmark pathological finding on muscle biopsy is the presence of centrally located nuclei in muscle fibers, resembling fetal myotubes. Affected newborns typically present with severe generalized weakness (floppy infant), feeding difficulties, and life-threatening respiratory failure. Additional features may include ophthalmoplegia (weakness of eye muscles), facial weakness, a long and narrow face, thin ribs, and undescended testes. Many affected males require long-term ventilatory support, and the condition carries significant mortality in infancy and early childhood, though some individuals survive into later childhood or adulthood with intensive supportive care. Complications can include hepatic peliosis (blood-filled cysts in the liver), which may lead to life-threatening hepatic hemorrhage. There is currently no approved curative treatment for X-linked centronuclear myopathy. Management is primarily supportive and multidisciplinary, including respiratory support (tracheostomy and mechanical ventilation), nutritional support via gastrostomy tube, physical therapy, and orthopedic management of skeletal complications. Gene therapy approaches targeting the MTM1 gene have been investigated in clinical trials, with some promising early results, though safety concerns including hepatotoxicity have been reported. Genetic counseling is important for affected families, and carrier testing and prenatal diagnosis are available.

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

Common questions about X-linked centronuclear myopathy