2026 ICD-10-CM Diagnosis Code E71.120Methylmalonic acidemia

AHRQ’s CCSR groups this code into broader clinical categories.

• Homocystinuria

  autosomal recessive inborn error of methionine metabolism usually caused by a deficiency of cystathionine beta-synthase and associated with elevations of homocysteine in plasma and urine. clinical features include a tall slender habitus, scoliosis, arachnodactyly, muscle weakness, genu varus, thin blond hair, malar flush, lens dislocations, an increased incidence of mental retardation, and a tendency to develop fibrosis of arteries, frequently complicated by cerebrovascular accidents and myocardial infarction. (from adams et al., principles of neurology, 6th ed, p979)

• Combined Methylmalonic Aciduria and Homocystinuria|Combined methylmalonic acidemia and homocystinuria due to defects in adenosylcobalamin and methylcobalamin synthesis

  a genetically heterogeneous disorder of cobalamin (cbl; vitamin b12) metabolism due to loss of function mutations in the enzymes that synthesize the coenzymes adenosylcobalamin (adocbl) and methylcobalamin (mecbl). this is a subtype of methylmalonic acidemia that includes complementation groups cblc, cbld, cblf, cblj, cbll and cblx.

• Arakawa Syndrome II|Arakawa's Syndrome 2|Arakawa's Syndrome II|Homocystinuria-Megaloblastic Anemia, cblG Complementation Type|Methionine Synthase Deficiency|Methylcobalamin Deficiency, cblG Type|Tetrahydrofolate Methyltransferase Deficiency|Tetrahydrofolate Methyltransferase Deficiency

  a rare autosomal dominant inherited metabolic disorder characterized by deficiency of the enzyme tetrahydrofolate-methyltransferase. it results in the abnormal metabolism of methylcobalamin. signs and symptoms include mental retardation, megaloblastic anemia, hypotonia, epilepsy, and hepatosplenomegaly.

• Homocystinuria

  an autosomal recessive inherited metabolic disorder caused by mutations in the cbs, mthfr, mtr, and mtrr genes. it is characterized by abnormalities in the methionine metabolism and is associated with deficiency of cystathionine synthase. it results in the accumulation of homocysteine in the serum. it may affect the cardiovascular, musculoskeletal and the central nervous systems.

• Homocystinuria-Megaloblastic Anemia, cblE Complementation Type|HMAE|Methylcobalamin Deficiency, cblE Type

  an autosomal recessive condition caused by mutation(s) in the mtrr gene, encoding methionine synthase reductase. it is characterized by homocystinuria and megaloblastic anemia.

• Methylmalonic Aciduria and Homocystinuria Type D Protein, Mitochondrial|C2orf25 Protein|MMADHC|Methylmalonic Aciduria, cblD Type, And Homocystinuria Protein|Uncharacterized Protein C2orf25, Mitochondrial

  methylmalonic aciduria and homocystinuria type d protein, mitochondrial (296 aa, ~33 kda) is encoded by the human mmadhc gene. this protein plays a role in vitamin metabolism.

• Methylmalonic Aciduria and Homocystinuria, cblC Type

  an autosomal recessive form of combined methylmalonic aciduria and homocystinuria, caused by mutation(s) in the mmachc gene, encoding methylmalonic aciduria and homocystinuria type c protein.

• Methylmalonic Aciduria and Homocystinuria, cblD Type|MAHCD

  an autosomal recessive form of combined methylmalonic aciduria and homocystinuria, caused by mutation(s) in the mmadhc gene, encoding cobalamin trafficking protein cbld.

• Methylmalonic Aciduria and Homocystinuria, cblF Type|MAHCF

  an autosomal recessive form of combined methylmalonic aciduria and homocystinuria, caused by mutation(s) in the lmbrd1 gene, encoding lysosomal cobalamin transport escort protein lmbd1.

• Methylmalonic Aciduria and Homocystinuria, cblJ Type|MAHCJ

  an autosomal recessive form of combined methylmalonic aciduria and homocystinuria, caused by mutation(s) in the abcd4 gene, encoding lysosomal cobalamin transporter abcd4.

• MMADHC Gene|MMADHC|MMADHC|Methylmalonic Aciduria (Cobalamin Deficiency) cblD Type, with Homocystinuria Gene

  this gene is involved in vitamin metabolism.

• MMADHC wt Allele|C2orf25|CL25022|Chromosome 2 Open Reading Frame 25 Gene|HSPC161|Methylmalonic Aciduria (Cobalamin Deficiency) cblD Type, with Homocystinuria wt Allele|Methylmalonic Aciduria, cblD Type, and Homocystinuria Gene|My011|cblD

  human mmadhc wild-type allele is located in the vicinity of 2q23.2 and is approximately 18 kb in length. this allele, which encodes methylmalonic aciduria and homocystinuria type d protein, mitochondrial, plays a role in the mediation of vitamin b12 metabolism. mutation of the gene is associated with some cases of homocystinuria, and methylmalonic aciduria.

• Cyanocobalamin Reductase / Alkylcobalamin Dealkylase|Alkylcobalamin:Glutathione S-Alkyltransferase|CblC|Cyanocobalamin Reductase (Cyanide-Eliminating)|EC 1.16.1.6|EC 2.5.1.15|MMACHC|Methylmalonic Aciduria and Homocystinuria Type C Protein

  cyanocobalamin reductase / alkylcobalamin dealkylase (282 aa, ~32 kda) is encoded by the human mmachc gene. this protein is involved in cobalamin transport and the decyanation of cyanocob(iii)alamin (cyanocobalamin, cncbl) to yield cob(ii)alamin and cyanide and the dealkylation of alkylcob(iii)alamins using a thiolate of glutathione to generate cob(i)alamin and the corresponding glutathione thioether.

• MMACHC wt Allele|DKFZP564I122|Metabolism of Cobalamin Associated C wt Allele|Methylmalonic Aciduria (Cobalamin Deficiency) cblC Type, with Homocystinuria Gene|cblC

  human mmachc wild-type allele is located in the vicinity of 1p34.1 and is approximately 13 kb in length. this allele, which encodes cyanocobalamin reductase / alkylcobalamin dealkylase protein, plays a role in cobalamin transport and the conversion of cyanocobalamin and alkylcobalamin to cobalamin. mutation of the gene is associated with methylmalonic aciduria and homocystinuria cblc type.

Metabolic Disorders

Metabolism is the process your body uses to get or make energy from the food you eat. Food is made up of proteins, carbohydrates, and fats. Chemicals in your digestive system break the food parts down into sugars and acids, your body's fuel.

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