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GTR Home > Conditions/Phenotypes > Homocystinuria without methylmalonic aciduria

Homocystinuria without methylmalonic aciduria

Summary

An inborn error of vitamin B12 (cobalamin) metabolism characterised by megaloblastic anaemia, encephalopathy and sometimes, developmental delay, and associated with homocystinuria and hyperhomocysteinemia. There are three types of homocystinuria without methylmalonic aciduria; cblE, cblG and cblD-variant 1 (cblDv1). These disorders are caused by a functional deficiency of the cytoplasmic enzyme methionine synthase (MS), which catalyses remethylation of homocysteine to form methionine. [from SNOMEDCT_US]

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