" /> Homocystinuria-megaloblastic anemia, cble complementation type - CISMeF





Preferred Label : Homocystinuria-megaloblastic anemia, cble complementation type;

Symbol : HMAE;

CISMeF acronym : HMAE;

Type : Phenotype, molecular basis known;

Alternative titles and symbols : Vitamin b12-responsive homocystinuria, cble type; Methylcobalamin deficiency, cble type; Homocystinuria-megaloblastic anemia due to defect in cobalamin metabolism, cble complementation type;

Description : Homocystinuria and megaloblastic anemia is an autosomal recessive inborn error of metabolism resulting from defects in the cobalamin (vitamin B12)-dependent pathway that converts homocysteine to methionine, which is catalyzed by methionine synthase (MTR; 156570). Clinical features are somewhat variable, but include delayed psychomotor development, hypotonia, megaloblastic anemia, homocystinuria, and hypomethioninemia, all of which respond to cobalamin supplementation. Methylmalonic aciduria is not present. Two complementation groups have been described based on fibroblast studies: CblE and CblG (250940) (Watkins and Rosenblatt, 1988). Cells from patients with CblE fail to incorporate methyltetrahydrofolate into methionine in whole cells, but cell extracts show normal methionine synthase activity in the presence of a reducing agent. Cells from patients with CblG have defects in the methionine synthase enzyme under both conditions (summary by Leclerc et al., 1996). CblG is caused by mutation in the MTR gene.;

Inheritance : Autosomal recessive;

Molecular basis : Caused by mutation in the methionine synthase reductase gene (MTRR, 602568.0001);

Laboratory abnormalities : Hypomethioninemia; Homocystinuria; Hyperhomocystinemia;

Prefixed ID : #236270;

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26/05/2024


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