描述
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.