Affiliations: Natural Sciences and Science Education, National
Institute of Education, Nanyang Technological University, Singapore
Note: [] Corresponding author: Mr. Chuanfei Chen, BLK 663A, #14-295,
Jurong West Street 65, 641663, Singapore. Tel.: +65 67925170; E-mail:
[email protected]
Abstract: The cystathionine β-synthase (CBS) 844ins68 polymorphism,
methionine synthase (MS) A2756G SNP, and 5,10-methylenetetrahydrofolate
reductase (MTHFR) C677T SNP are associated with homocysteine (Hcy) level in
humans. Elevated Hcy level is considered a risk factor for atherosclerotic
diseases among Asian populations. Therefore, the three polymorphisms may vary
the risk for developing such diseases in Singaporeans. In this study, the three
polymorphisms were determined in a group of unrelated healthy Singaporeans (273
Chinese, 127 Indians, and 156 Malays). Regarding allele frequencies, Indians
had the highest frequencies of the CBS insertion allele (2.0%) and the MS 2756G
allele (26.4%), while Chinese had the highest MTHFR 677T allele frequency
(27.5%). In addition, the MTHFR 677T allele was found significantly lower in
Chinese males than in their female counterparts. As the CBS insertion allele
was suggested to be associated with lower Hcy level, whereas the MS 2756G
allele and the MTHFR T/T genotype were related to higher Hcy level, the MS A/G
or G/G genotype and the MTHFR T/T genotype were considered double genetic risk
factors for elevated Hcy level. The frequency of such double genetic risk was
0.7% (4 subjects) in the total population consisting of 3 Chinese (1.1%) and 1
Malays (0.6%). No MTHFR T/T genotype was found in Indians. Such results
suggested that Chinese could have higher Hcy levels than Malays while the
situation for Indians was complicated. Since human Hcy levels are also affected
by environmental factors, further studies are required to better evaluate the
association between these three polymorphisms and Hcy levels and/or disease
susceptibilities in Singaporeans.
