meth·yl·ma·lon·ic·ac·i·de·mia (meth″əl-mə-lon″ik-as″ĭ-deґme-ə) 1. a genetically heterogeneous, autosomal recessive aminoacidopathy characterized by an 2. excess of methylmalonic acid in the blood and urine, with metabolic ketoacidosis, hyperglycinemia, hyperglycinuria, and hyperammonemia, and presenting in infancy as failure to thrive, persistent vomiting and dehydration, respiratory distress, and hypotonia. It results from any of several defects that cause deficiency of methylmalonyl-CoA mutase (q.v.) activity, including defects in the apoenzyme, in the biosynthesis of adenosylcobalamin (see cob(1)alamin adenosyltransferase and cobalamin reductase), in the transport of cobalamin, or in the pathway of biosynthesis common to both cobalamin-containing coenzymes; the last two defects also cause homocystinuria due to deficiency of methionine synthase (q.v.). Called also methylmalonicaciduria. excess of methylmalonic acid in the blood.

Medical dictionary. 2011.

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  • Methylmalonicaciduria — An inherited metabolic (biochemical) disease that causes young children to become mentally retarded. The defect in some (but not all) of these children has to do with an inability to use the vitamin B12 they ingest. If these children are given… …   Medical dictionary

  • List of diseases (M) — A list of diseases in the English wikipedia.DiseasesTOC MaMac* Mac Ardle disease * Mac Dermot Patton Williams syndrome * Mac Dermot Winter syndromeMaci Macr* Macias Flores Garcia Cruz Rivera syndrome * Mackay Shek Carr syndrome * Macleod Fraser… …   Wikipedia

  • Vitamin B12-responsive methylmalonicaciduria — An inherited metabolic (biochemical) disease that, unless effectively treated, causes young children to become mentally retarded. The defect in some (but not all) of these children has to do with an inability to use the vitamin B12 they ingest.… …   Medical dictionary

  • methylmalonic acid — 2 Methylpropanedioic acid, an important intermediate in fatty acid metabolism; seen in elevated levels in cases of vitamin B12 deficiency. Note that methylmalonate is not methyl malonate, which is the dimethyl ester of malonate. SYN: isosuccinic… …   Medical dictionary

  • cob(I)alamin adenosyltransferase — co·b(I)al·a·min ad·e·no·syl·trans·fer·ase (ko balґə min ə den″o səl transґfər ās) a mitochondrial enzyme of the transferase class that catalyzes the transfer of an adenosyl group to cobalamin from ATP, forming the… …   Medical dictionary

  • cobalamin reductase — co·bal·amin re·duc·tase (ko balґə min re dukґtās) either of two mitochondrial reductases that catalyze steps in the synthesis of adenosylcobalamin from hydroxocobalamin; deficiency of one or both is believed to be a cause of… …   Medical dictionary

  • ketotic hyperglycinemia — 1. the elevated accumulation and excretion of glycine accompanied by ketosis that is secondary to propionicacidemia, methylmalonicacidemia, and other organic acidemias, as distinguished from nonketotic hyperglycinemia. 2. propionicacidemia (def.… …   Medical dictionary

  • methionine synthase — me·thi·o·nine syn·thase (mə thiґo nēn synґthās) [EC] an enzyme of the transferase class that catalyzes the remethylation of homocysteine to form methionine, using 5 methyltetrahydrofolate as a methyl donor and requiring… …   Medical dictionary

  • methylmalonyl-CoA mutase — meth·yl·mal·o·nyl CoA mu·tase (meth″əl malґə nəl ko aґ muґtās) [EC] an enzyme of the isomerase class that catalyzes the isomerization of L methylmalonyl coenzyme A to succinyl coenzyme A, requiring… …   Medical dictionary

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