Hypermethioninemia


Hypermethioninemia is caused by a defect in the AHCY gene which codes for Adenosylhomocysteinase. converts the S-adenosyl homocysteine into the compound homocysteine. Homocysteine may be converted back to methionine or into another amino acid, cysteine. A defect in this enzyme results in accumulation of methionine and cysteine in blood. People with hypermethioninemia often do not show any symptoms. Some individuals with hypermethioninemia exhibit learning disabilities, mental retardation, and other neurological problems; delays in motor skills such as standing or walking; sluggishness; muscle weakness; liver problems; unusual facial features; and their breath, sweat, or urine may have a smell resembling boiled cabbage.

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References

  1. Uniprot: Q00266
  2. OMIM: Entry 250850
  3. Blom HJ, Davidson AJ, Finkelstein JD, Luder AS, Bernardini I, Martin JJ, Tangerman A, Trijbels JM, Mudd SH, Goodman SI, et al.: Persistent hypermethioninaemia with dominant inheritance. J Inherit Metab Dis. 1992;15(2):188-97. Pubmed
  4. Chamberlin ME, Ubagai T, Mudd SH, Levy HL, Chou JY: Dominant inheritance of isolated hypermethioninemia is associated with a mutation in the human methionine adenosyltransferase 1A gene. Am J Hum Genet. 1997 Mar;60(3):540-6. Pubmed
  5. Finkelstein JD, Kyle WE, Martin JJ: Abnormal methionine adenosyltransferase in hypermethioninemia. Biochem Biophys Res Commun. 1975 Oct 27;66(4):1491-7. Pubmed
  6. Gaull GE, Tallan HH, Lonsdale D, Przyrembel H, Schaffner F, von Bassewitz DB: Hypermethioninemia associated with methionine adenosyltransferase deficiency: clinical, morphologic, and biochemical observations on four patients. J Pediatr. 1981 May;98(5):734-41. Pubmed