XLMTM genetic cause and inheritance

XLMTM is a genetic disease

X-linked myotubular myopathy (XLMTM) is caused by mutations in the MTM1 gene, which encodes myotubularin, a protein required for the normal development, organization, and function of skeletal muscle cells.1-3 Approximately 400 unique mutations in the MTM1 gene have been associated with XLMTM in patients.4

The MTM1 gene is located on the X chromosome, and XLMTM is inherited in an X-linked recessive manner.1,2

If a father has XLMTM, all of his daughters will become carriers of XLMTM. Daughters/female carriers are frequently asymptomatic, but some present with mild to severe limb weakness, asymmetric muscle loss, respiratory failure, facial weakness, ptosis, and ophthalmoparesis.5,6

If a mother carries a mutation in the MTM1 gene, each of her daughters has a 50% chance of becoming a carrier and each of her sons has a 50% chance of having XLMTM.

If a father has XLMTM, all of his daughters will become carriers of XLMTM. Daughters/female carriers are frequently asymptomatic, but some present with mild to severe limb weakness, asymmetric muscle loss, respiratory failure, facial weakness, ptosis, and ophthalmoparesis.5,6

If a mother carries a mutation in the MTM1 gene, each of her daughters has a 50% chance of becoming a carrier and each of her sons has a 50% chance of having XLMTM.

Due to its X-linked recessive inheritance pattern, XLMTM affects male patients. Its incidence is estimated at 1 in 40,000 to 50,000 newborn males.2,7

References

1. McEntagart M, et al. Neuromuscul Disord. 2002;12(10):939-946. 2. Graham RJ, et al. Arch Dis Child. 2020;105(4):332-338. 3. Dowling JJ, et al. In: Adam MP, et al, eds. GeneReviews®. 2002. 4. Biancalana V, et al. Eur J Hum Genet. 2012;20(10):1-5. 5. Biancalana V, et al. Acta Neuropathol. 2017;134(6):889-904. 6. Cocanougher BT, et al. Neurology. 2019;93(16):e1535-e1542. 7. Vandersmissen I, et al. Neuromuscul Disord. 2018;28(9):766-777.

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