slowly progressive generalized muscle weakness and atrophy beginning in childhood; on biopsy of skeletal muscle, the nuclei of most muscle fibers are seen to be located near the center of a small fiber (the normal position for a 10-week embryo) rather than at the periphery of the fiber; familial incidence. Autosomal dominant [MIM*160150] recessive [MIM*255200] and X-linked [310400] forms occur. The X-linked form is caused by mutation in the myotubular myopathy gene (MTM1) on Xq28. SYN: myotubular myopathy.
