McLeod syndrome
From Wikipedia, the free encyclopedia
- This article is about the genetic disease of the blood, not MacLeod's syndrome (the lung disease).
McLeod syndrome (or McLeod phenomenon) is a genetic disorder caused by presence of the McLeod phenotype, a recessive anomaly on the X chromosome which alters production of XK protein (a precursor of Kell antigens on the surface of red blood cells).
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[edit] History
McLeod syndrome was discovered in 1961 and, as with the Kell antigen system, was named after the first patient in which it was found: a Harvard dental student Hugh McLeod, whose red blood cells were observed to be hemolysed during blood donation,<ref>Allen FH Jr, Krabbe SM, Corcoran PA. A new phenotype (McLeod) in the Kell blood-group system. Vox Sang. 1961 Sep;6:555-60. PMID 13477267</ref> and his red cells were found to be acanthocytic (spiky) under the microscope.
[edit] Genetics
The McLeod phenotype is a recessive mutation of the Kell blood group system. The McLeod gene encodes the XK protein, which is located on the X chromosome, and has the structural characteristics of a membrane transport protein but an unknown function. Absence of the XK protein is an X-linked disease. <ref>Ho MF, Monaco AP, Blonden LA, van Ommen GJ, Affara NA, Ferguson-Smith MA, Lehrach H. Fine mapping of the McLeod locus (XK) to a 150-380-kb region in Xp21. Am J Hum Genet. 1992 Feb;50(2):317-30. PMID 1734714</ref> Mutational variants result in McLeod syndrome either with or without neuroacanthocytosis: the gene on the X chromosome for McLeod syndrome is physically close to the gene for chronic granulomatous disease. As a result, individuals with one disease may have both. <ref>Marsh WL, Oyen R, Nichols ME, Allen FH Jr. Chronic granulomatous disease and the Kell blood groups. Br J Haematol. 1975 Feb;29(2):247-62. PMID 1191546</ref>
[edit] Epidemiology and disease associations
McLeod syndrome is present in 0.5 to 1 per 100,000 of the population. McLeod males have variable acanthocytosis due to a defect in the inner leaflet bilayer of the red blood cell, as well as mild hemolysis. McLeod females have only occasional acanthocytes and very mild hemolysis; the lesser severity is thought to be due to X chromosome inactivation via the Lyon effect. Some individuals with McLeod phenotype develop myopathy, neuropathy or psychiatric symptoms, producing a syndrome that may mimic chorea.<ref>Danek A, Rubio JP, Rampoldi L, Ho M, Dobson-Stone C, Tison F, Symmans WA, Oechsner M, Kalckreuth W, Watt JM, Corbett AJ, Hamdalla HH, Marshall AG, Sutton I, Dotti MT, Malandrini A, Walker RH, Daniels G, Monaco AP. McLeod neuroacanthocytosis: genotype and phenotype. Ann Neurol. 2001 Dec;50(6):755-64. PMID 11761473</ref><ref>Malandrini A, Fabrizi GM, Truschi F, Di Pietro G, Moschini F, Bartalucci P, Berti G, Salvadori C, Bucalossi A, Guazzi G. Atypical McLeod syndrome manifested as X-linked chorea-acanthocytosis, neuromyopathy and dilated cardiomyopathy: report of a family. J Neurol Sci. 1994 Jun;124(1):89-94. PMID 7931427</ref>
McLeod syndrome can cause an increase in the enzymes creatine kinase (CK) and lactate dehydrogenase (LDH) found in routine blood screening. <ref>Oechsner M, G. Winkler G, A. Danek A, McLeod neuroacanthocytosis: An underdiagnosed syndrome? International communication forum in human molecular genetics Sep 6 1995 [1]</ref> <ref>Neuromuscular Disease Center Dilated cardiomyopathies ± Myopathy</ref>
[edit] Treatment
There is no cure for McLeod syndrome, but treatment is supportive depending on symptoms. Medication may assist management of epilepsy, cardiac and psychiatric features, although patients may respond poorly to treatment for chorea.
[edit] External links
- Mendelian Inheritance in Man (OMIM) 314850 OMIM entry on Kell blood group precursor, XK
[edit] Notes
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