Audentes Therapeutics announced that the U.S. Food and Drug Administration (FDA) has lifted the clinical hold for the ASPIRO clinical trial evaluating AT132 in patients with X-linked myotubular myopathy (XLMTM). XLMTM is a serious, life-threatening neuromuscular disease characterized by extreme muscle weakness, respiratory failure, and early death. The company is now working to complete all clinical and regulatory activities necessary to resume dosing and plans to have discussions at a future date with the regulators on the path forward toward global registration filings for AT132. XLMTM is a serious, life-threatening, rare neuromuscular disease that is characterized by extreme muscle weakness, respiratory failure and early death. Mortality rates are estimated to be 50% in the first 18 months of life. For those patients who survive past infancy, there is an estimated additional 25 percent mortality by the age of 10. XLMTM is caused by mutations in the MTM1 gene that lead to a lack or dysfunction of myotubularin, a protein that is needed for normal development, maturation and function of skeletal muscle cells. The disease affects approximately 1 in 40,000 to 50,000 newborn males. XLMTM places a substantial burden of care on patients, families and the healthcare system, including high rates of healthcare utilization, hospitalization and surgical intervention. More than 80 percent of XLMTM patients require ventilator support, and the majority of patients require a gastrostomy tube for nutritional support. In most patients, normal developmental motor milestones are delayed or never achieved. Currently, only supportive treatment options, such as ventilator use or a feeding tube, are available.