Nitima Chanarat. The association of methylene tetrahydrofolate reductase (MTHFR) and endothelial nitric oxide synthase (eNOS) gene polymorphisms with homocysteine levels and carotid intima-media thickness in thai chronic hemodialysis patients. Master's Degree(Biochemistry). Mahidol University. : Mahidol University, 2008.
The association of methylene tetrahydrofolate reductase (MTHFR) and endothelial nitric oxide synthase (eNOS) gene polymorphisms with homocysteine levels and carotid intima-media thickness in thai chronic hemodialysis patients
Abstract:
Cardiovascular disease (CVD), the major cause of death in hemodialysis (HD)
patients, is now recognized as a multifactorial disease with numerous genes and
environmental factors. During the past years, many candidate genes for atherosclerosis
have been reported. The early atherosclerotic changes can be effectively detected by
measuring carotid intima-media thickness (CIMT). Genetic variants of methylene
tetrahydrofolate reductase (MTHFR) and endothelial nitric oxide synthase (eNOS) have
been shown as potential factors in the prognosis of atherosclerosis in HD patients. The
aim of this study was to assess the relationships between polymorphisms of genes
encoding MTHFR (C677T & A1298C), eNOS (G894T) and homocysteine (hcy) levels as
well as CIMT in Thai chronic HD patients. The study subjects comprised of 28 HD
patients with coronary artery disease (CAD) and 74 HD patients without CAD. MTHFR
and eNOS gene polymorphisms were determined by PCR-RFLP. Plasma hcy levels were
determined by Fluorescence Polarization Immunoassay methods and CIMT was
measured by ultrasound. It was found that the distribution of MTHFR and eNOS
genotypes were not significantly different between HD patients with or without CAD.
Mean plasma hcy levels were significantly higher in HD patients with CAD who carried
CT or TT genotype than those who carried the CC genotype (29.43 + 12.0 μmol/L vs
21.16 + 5.61 μmol/L, P= 0.012) On the contrary, mean plasma hcy levels were not
significantly different in HD patients without CAD, who carried CT or TT genotype, than
those who carried the CC genotype (25.16 + 6.15 μmol/L vs 23.54 + 6.62 μmol/L, P=
0.323). The compound heterozygosity of 677CT/1298AC MTHFR variants showed slight
elevation of plasma hcy in HD patients with CAD when compared with HD patients
without CAD. Using multiple linear regression analysis for the predictors of plasma hcy
levels, MTHFR C677T genotype and gender were significant (P=0.017 and P= 0.005,
respectively). In addition, there was no significant association between CIMT and
MTHFR or eNOS gene polymorphisms, although a slightly greater CIMT was observed
in HD patients with CAD who carried CT or TT genotypes. It was found using multiple
regression analysis that age, male gender and hs-CRP were independently associated with
CIMT. In addition multiple stepwise logistic regression analysis identified CIMT
(OR=28.7, 95%CI: 2.637-312.4, P=0.006) as a factor associated with CAD in HD
patients. This study demonstrated that MTHFR C677T or A1298C polymorphisms and
eNOS G894T polymorphism were not associated with the presence of CAD in Thai
chronic HD patients.