X-linked Myotubular Myopathy
X-linked myotubular myopathy (XLMTM) is a genetic neuromuscular disorder that varies in severity, but is generally classified by muscular weakness throughout the body. It is caused by mutations to the myotubularin (MTM1) gene. Symptoms are often present at birth, though may develop later in infancy or early childhood. Rarely, symptoms may not present until adolescence or adulthood. Common symptoms include mild to profound muscle weakness, diminished muscle tone (hypotonia or "floppiness"), feeding difficulties, and potentially severe breathing complications. Many severely affected XLMTM infants will die within weeks or months of birth, although some individuals live until adulthood. XLMTM affects males, although females can be carriers. It occurs at a rate of 1 in every 50,000 births worldwide.