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Methylenetetrahydrofolate reductase deficiency is the most common genetic cause of elevated serum levels of homocysteine (hyperhomocysteinemia). It is caused by genetic defects in MTHFR, which is an important enzyme in the methyl cycle. [1] Common variants of MTHFR deficiency are asymptomatic and have only minor effects on disease risk. [2]
Individuals of 677TT are predisposed to mild hyperhomocysteinemia (high blood homocysteine levels), because they have less active MTHFR available to produce 5-methyltetrahydrofolate (which is used to decrease homocysteine). Low dietary intake of the vitamin folate can also cause mild hyperhomocysteinemia. Low folate intake affects individuals ...
As a consequence of the biochemical reactions in which homocysteine is involved, deficiencies of vitamin B 6, folic acid (vitamin B 9), and vitamin B 12 can lead to high homocysteine levels. [2] Other possible causes of hyperhomocysteinemia include genetics, excessive methionine intake, and other diseases.
Total plasma homocysteine. Homocysteine levels typically are higher in men than women, and increase with age. [15] [16] Common levels in Western populations are 10 to 12 μmol/L, and levels of 20 μmol/L are found in populations with low B-vitamin intakes or in the elderly (e.g., Rotterdam, Framingham). [17] [18]
Hence treatment includes both betaine and a diet low in methionine. In classical homocystinuria (CBS, or cystathione beta synthase deficiency), the plasma methionine level usually increases above the normal range of 30 micromoles/L and the concentrations should be monitored as potentially toxic levels (more than 400 micromoles/L) may be reached.
Both adults and children need folate to make normal red and white blood cells and prevent anemia, which causes fatigue, weakness, and inability to concentrate. [115] [116] Increased homocysteine levels suggest tissue folate deficiency, but homocysteine is also affected by vitamin B 12 and vitamin B 6, renal function, and
Hyperhomocysteinemia is a medical condition characterized by an abnormally large level of homocysteine in the blood. Mutations in CBS are the single most common cause of hereditary hyperhomocysteinemia. Genetic defects that affect the MTHFR, MTR, and MTRR/MS enzyme pathways can also contribute to high homocysteine levels. Inborn errors in CBS ...
4548 238505 Ensembl ENSG00000116984 ENSMUSG00000021311 UniProt Q99707 A6H5Y3 RefSeq (mRNA) NM_000254 NM_001291939 NM_001291940 NM_001081128 RefSeq (protein) NP_000245 NP_001278868 NP_001278869 NP_001074597 Location (UCSC) Chr 1: 236.8 – 236.92 Mb Chr 13: 12.2 – 12.27 Mb PubMed search Wikidata View/Edit Human View/Edit Mouse Methionine synthase (MS, MeSe, MTR) is primarily responsible for ...