TITLE

Polymorphisms in MTHFR, MS and CBS Genes and Homocysteine Levels in a Pakistani Population

AUTHOR(S)
Yakub, Mohsin; Moti, Naushad; Parveen, Siddiqa; Chaudhry, Bushra; Azam, Iqbal; Iqbal, Mohammad Perwaiz
PUB. DATE
March 2012
SOURCE
PLoS ONE;Mar2012, Vol. 7 Issue 3, p1
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Background: Hyperhomocysteinemia (>15 mmol/L) is highly prevalent in South Asian populations including Pakistan. In order to investigate the genetic determinants of this condition, we studied 6 polymorphisms in genes of 3 enzymes - methylenetetrahydrofolate reductase (MTHFR; C677T; A1298C), methionine synthase (MS; A2756G), cystathionine-�-synthase (CBS; T833C/844ins68, G919A) involved in homocysteine metabolism and investigated their interactions with nutritional and environmental factors in a Pakistani population. Methodology/Principal Findings: In a cross-sectional survey, 872 healthy adults (355 males and 517 females; age 18-60 years) were recruited from a low-income urban population in Karachi. Fasting venous blood was obtained and assessed for plasma/serum homocysteine; folate, vitamin B12, pyridoxal phosphate and blood lead. DNA was isolated and genotyping was performed by PCR-RFLP (restriction-fragment-length- polymorphism) based assays. The average changes in homocysteine levels for MTHFR 677CT and TT genotypes were positive [� (SE �), 2.01(0.63) and 16.19(1.8) mmol/L, respectively]. Contrary to MTHFR C677T polymorphism, the average changes in plasma homocysteine levels for MS 2756AG and GG variants were negative [� (SE �), 20.56(0.58) and 20.83(0.99) mmol/L, respectively]. The average change occurring for CBS 844ins68 heterozygous genotype (ancestral/insertion) was 21.88(0.81) mmol/L. The combined effect of MTHFR C677T, MS A2756G and CBS 844ins68 genotypes for plasma homocysteine levels was additive (p value <0.001). Odds of having hyperhomocysteinemia with MTHFR 677TT genotype was 10-fold compared to MTHFR 677CC genotype [OR (95%CI); 10.17(3.6-28.67)]. Protective effect towards hyperhomocysteinemia was observed with heterozygous (ancestral/insertion) genotype of CBS 844ins68 compared to homozygous ancestral type [OR (95% CI); 0.58 (0.34-0.99)]. Individuals with MTHFR 677CT or TT genotypes were at a greater risk of hyperhomocysteinemia in folate and vitamin B12 deficiencies and high blood lead (p value <0.05) level. Conclusions: Gene polymorphism (especially MTHFR C677T transition), folate and vitamin B12 deficiencies, male gender and high blood lead level appear to be contributing towards the development of hyperhomocysteinemia in a Pakistani population.
ACCESSION #
77585364

 

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