Myotubular myopathy only affects muscles and does not impact intelligence in any shape or form.X-linked myotubular myopathy was traditionally a fatal condition of infancy, with life expectancy of usually less than two years. There appears to be substantial variability in the clinical severity for different genetic abnormalities at that same MTM1 gene. Further, published cases show significant differences in clinical severity among relatives with the same genetic abnormality at the MTM1 gene. Most truncating mutations of MTM1 cause a severe and early lethal phenotype, while some missense mutations are associated with milder forms and prolonged survival (up to 54 years).Centronuclear myopathies typically have a milder presentation and a better prognosis. Autosomal dominant CNM tends to have a less severe phenotype than the autosomal recessive version. Recently, researchers discovered mutations at the gene dynamin 2 (DNM2 on chromosome 19, at site 19p13.2), responsible for the autosomal dominant form of centronuclear myopathy. This condition is now known as dynamin 2 centronuclear myopathy (abbreviated DNM2-CNM). Research has indicated that patients with DNM2-CNM have a slowly progressive muscular weakness usually beginning in adolescence or early adulthood, with an age range of 12 to 74 years. Genetic
The genetic abnormality associated with the X-linked form of myotubular myopathy (XLMTM) was first localized in 1990 to the X chromosome at site Xq28. MTM1 codes for the myotubularin protein, a highly conserved lipid phosphatase involved in cellular transport, trafficking and signalling.
Approximately 80% of males with myotubular myopathy diagnosed by muscle biopsy have mutations in MTM1, and about 7% of these mutations are genetic deletions.Centronuclear myopathies where the genetic abnormality is NOT sex-linked (e.g., not located on the X chromosome) are considered autosomal. Autosomal abnormalities can either be dominant or recessive, and are often referred to as AD for "autosomal dominant" or AR for "autosomal recessive").Many researchers use the term "myotubular myopathy" (MTM) only for cases when the genetic test has come back positive for abnormalities (genetic mutations) at the MTM1 gene on the X chromosome. Cases with a centronuclear (nucleus in the center) appearance on muscle biopsy but a normal genetic test for MTM1 would be referred to as centronuclear myopathy until such time as a specific genetic site is identified to give a more detailed sub-classification.The possible combinations of inheritance of myotubular myopathy are as follows:

Sporadic cases have also been reported where there is no previous family history (these cases are presumably due to a new mutation that was not present in either parent). Pathology
On examination of muscle biopsy material, the nuclear material is located predominantly in the center of the muscle cells, and is described as having any "myotubular" or "centronuclear" appearance. In terms of describing the muscle biopsy itself, "myotubular" or "centronuclear" are almost synonymous, and both terms point to the similar cellular-appearance among MTM and CNM.