| methylmalonic acidaemia | <biochemistry> A group of inherited metabolic disorders that result in the accumulation of methylmalonic acid in the bloodstream. This leads to a severe metabolic acidosis (and ketosis) that can be fatal. A defect in the metabolic pathway of methylmalonic acid, vitamin B12 and succinic acid is the underlying cause. An infection can trigger a bout of acidosis. A low protein diet is essential in these patients. Occasionally large doses of vitamin B12 or an alkalinising agent (bicarbonate) will be necessary to treat acute exacerbations of acidosis. Origin: Gr. Haima = blood (27 Sep 1997) |
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| methylmalonic acid | <chemical> Methylpropanedioic acid. A malonic acid derivative which is a vital intermediate in the metabolism of fat and protein. Abnormalities in methylmalonic acid metabolism lead to methylmalonic aciduria. This metabolic disease is attributed to a block in the enzymatic conversion of methylmalonyl CoA to succinyl CoA. Chemical name: Propanedioic acid, methyl- (12 Dec 1998) |
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| methylmalonic acidemia | ketotic hyperglycinaemia |
| methylmalonic aciduria | Excretion of excessive amounts of methylmalonic acid in urine owing to deficient activity of methylmalonyl-CoA mutase or deficient cobalamin reductase. Two types occur: 1) an inborn error of metabolism resulting in severe ketoacidosis shortly after birth, with long-chain urinary ketones; autosomal recessive inheritance; 2) acquired, a type due to vitamin B12 deficiency due to defective synthesis of adenosylcobalamin. (05 Mar 2000) |