MTRR and MTHFR polymorphism: Link to Down syndrome?

TLDR

Polymorphisms in the folate‑metabolizing enzymes MTHFR C677T and MTRR A66G have been linked to the etiology of Down syndrome. The study examined the prevalence of these variant genotypes in mothers of children with Down syndrome versus control mothers and investigated biochemical factors influenced by MTRR A66G and MTHFR C677T. They compared genotype frequencies in 48 mothers of Down syndrome children and 192 control mothers and assessed plasma homocysteine levels. MTRR A66G variant genotypes were significantly more frequent in mothers of Down syndrome children (P = 0.0028), and mothers with both MTRR GG and MTHFR CT/TT genotypes had a 2.98‑fold increased risk (P = 0.02); MTHFR C677T alone was not associated, MTRR did not raise homocysteine, but the MTHFR T allele did. Published 2001 Wiley‑Liss, Inc.

Abstract

Abstract Polymorphisms in genes encoding the folate metabolizing enzymes methylenetetrahydrofolate reductase ( MTHFR C677T) and methionine synthase reductase ( MTRR A66G) have been linked to the etiology of Down syndrome. We examined the prevalence of these variant genotypes in mothers who had given birth to a child with Down syndrome (n = 48) and in control mothers (n = 192), and investigated the biochemical factors influenced by the presence of MTRR A66G and MTHFR C677T. The frequency of the MTRR variant genotypes (AG, GG) was significantly higher in mothers of children with Down syndrome compared to controls ( P = 0.0028). MTHFR C677T genotype frequencies were not significantly altered in mothers of children with Down syndrome ( P = 0.74). However, mothers who had a MTHFR CT or TT genotype and a MTRR GG genotype had a 2.98‐fold increased risk of having a child with Down syndrome ( P = 0.02). The MTRR polymorphism did not increase plasma homocysteine. Higher homocysteine was found with the presence of the MTHFR T allele. In conclusion, MTRR A66G is significantly more common in mothers of children with Down syndrome but does not appear to increase the risk for Down syndrome by changing homocysteine metabolism. Women who have both the MTRR and MTHFR variant genotypes are also at increased risk of producing offspring with Down syndrome. Published 2001 Wiley‐Liss, Inc.