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.
Differential diagnosis
A thyroid adenoma is distinguished from a multinodular goiter of the thyroid in that an adenoma is typically solitary, and is a neoplasm resulting from a genetic mutation (or other genetic abnormality) in a single precursor cell. In contrast, a multinodular goiter is usually thought to result from a hyperplastic response of the entire thyroid gland to a stimulus, such as iodine deficiency. Careful pathological examination may be necessary to distinguish a thyroid adenoma from a minimally invasive follicular thyroid carcinoma. Management
Most patients with thyroid adenoma can be managed by watchful waiting (without surgical excision) with regular monitoring. However, some patients still choose surgery after being fully informed of the risks. Regular monitoring mainly consists of watching for changes in nodule size and symptoms, and repeat ultrasonography or needle aspiration biopsy if the nodule grows. For patients with benign thyroid adenomata, thyroid lobectomy and isthmusectomy is a sufficient surgical treatment. This procedure is also adequate for patients with minimally invasive thyroid cancer. When histological examination shows no signs of malignancy, then no further intervention is required. These patients should continue to have their thyroid hormone status regularly checked. References


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