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Home > D. General pathology > Genetic and developmental anomalies > Genetic metabolic diseases > homocysteinemia



Monday 17 November 2003

Various genetic anomalies cause of elevated concentrations of homocysteine (homocystine) in plasma (or serum).

Homocysteinemia is seen in:

- homocystinuria (MIM.236200), a disorder most commonly due to cystathione beta-synthase deficiency
- vitamin B12 metabolic defect (MIM.277400, MIM.277410)
selective intestinal malabsorption of vitamin B12 (MIM.261100)
- N(5,10)-methylenetetrahydrofolate reductase deficiency (MIM.236250)
- methylcobalamin deficiency cbl G type (MIM.250940)
- transcobalamin II deficiency (MIM.275350)
- vitamin B12-responsive homocystinuria cbl G type (MIM.250940).


- methionine synthase deficiency by mutations of gene MTR (1p43)

  • Mutations in the MTR gene result in the methylcobalamin deficiency G (cblG) disorder, which is characterized by homocystinuria, hyperhomocysteinemia, and hypomethioninemia.