X-linked spinal muscular atrophy type 2

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X-linked spinal muscular atrophy type 2
Other namesSpinal muscular atrophy with arthrogryposis
X-linked recessive.svg
This condition is inherited in an X-linked recessive manner

X-linked spinal muscular atrophy type 2 (SMAX2, XLSMA), also known as arthrogryposis multiplex congenita X-linked type 1 (AMCX1), is a rare neurological disorder involving death of motor neurons in the anterior horn of spinal cord resulting in generalised muscle wasting (atrophy). The disease is caused by a mutation in UBA1 gene and is passed in an X-linked recessive manner by carrier mothers to affected sons.[1][2]

Affected babies have general muscle weakness, weak cry and floppy limbs; consequently, the condition is usually apparent at or even before birth. Symptoms resemble the more severe forms of the more common spinal muscular atrophy (SMA); however, SMAX2 is caused by a different genetic defect and only genetic testing can correctly identify the disease.[citation needed]

The disorder is usually fatal in infancy or early childhood due to progressive respiratory failure, although survival into teenage years have been reported.[3] As with many genetic disorders, there is no known cure to SMAX2. Appropriate palliative care may be able to increase quality of life and extend lifespan.[citation needed]

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  1. ^ Ramser, J.; Ahearn, M. E.; Lenski, C.; Yariz, K. O.; Hellebrand, H.; Von Rhein, M.; Clark, R. D.; Schmutzler, R. K.; Lichtner, P.; Hoffman, E. P.; Meindl, A.; Baumbach-Reardon, L. (2008). "Rare Missense and Synonymous Variants in UBE1 Are Associated with X-Linked Infantile Spinal Muscular Atrophy". The American Journal of Human Genetics. 82 (1): 188–193. doi:10.1016/j.ajhg.2007.09.009. PMC 2253959. PMID 18179898.
  2. ^ Dressman, D.; Ahearn, M. E.; Yariz, K. O.; Basterrecha, H.; Martínez, F.; Palau, F.; Barmada, M. M.; Clark, R. D.; Meindl, A.; Wirth, B.; Hoffman, E. P.; Baumbach-Reardon, L. (2007). "X-linked infantile spinal muscular atrophy: Clinical definition and molecular mapping". Genetics in Medicine. 9 (1): 52–60. doi:10.1097/GIM.0b013e31802d8353. PMID 17224690.
  3. ^ Kobayashi, H.; Baumbach, L.; Matise, T. C.; Schiavi, A.; Greenberg, F.; Hoffman, E. (1995). "A gene for a severe lethal form of X-linked arthrogryposis (X-linked infantile spinal muscular atrophy) maps to human chromosome Xp11.3–q11.2". Human Molecular Genetics. 4 (7): 1213–1216. doi:10.1093/hmg/4.7.1213. PMID 8528211.

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