The relationship between MTHFR gene polymorphisms, plasma homocysteine levels and diabetic retinopathy in type 2 diabetes mellitus / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To evaluate the role of methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and plasma homocysteine levels in patients with type 2 diabetes mellitus and diabetic retinopathy (DR).</p><p><b>METHODS</b>Total of 208 patients with type 2 diabetes mellitus and 57 controls were recruited into the study. MTHFR genetic C677T polymorphisms were determined by PCR-RFLP. Plasma total homocysteine levels were measured using high-performance liquid chromatography (HPLC) with fluorescence detection.</p><p><b>RESULTS</b>The frequencies of MTHFR TT homogeneous type, CT heterogeneous type and allele T (28.18%, 41.82%, 49.09%) were significantly higher in the type 2 diabetes mellitus with diabetic retinopathy group than those without retinopathy (18.37%, 29.59%, 33.16%) and those of controls (17.54%, 28.07%, 31.58%). The presence of the T allele appeared to have a strong association with the development of diabetic retinopathy. The odds ratio was 1.94 with a 95% confidence interval of 1.31 - 2.88. Moreover, plasma homocysteine levels were remarkably higher in patients with TT or CT genotype than in patients with the CC genotype.</p><p><b>CONCLUSION</b>MTHFR gene C677T mutation associated with a predisposition to increased plasma homocysteine levels may be considered as a genetic risk factor for diabetic microangiopathy (such as DR) in Chinese patients with type 2 diabetes mellitus.</p>

Association of polymorphism in neurogenic differentiation factor 1 gene with type 2 diabetes / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To evaluate the role of polymorphism in the neurogenic differentiation factor 1(Neuro D) gene in Chinese patients with type 2 diabetes mellitus.</p><p><b>METHODS</b>The genotypes of codon 45 variant (GCC-->ACC) in the Neuro D gene were determined by mismatch PCR-restriction fragment length polymorphism assay in 448 Chinese, including 124 subjects with normal glucose tolerance and 324 patients with type 2 diabetes mellitus. The diabetic patients were divided into two groups cutting off with the age of 40 at onset.</p><p><b>RESULTS</b>No homozygote of the Ala45Thr variant was found in these subjects. The frequencies of AT heterozygous type were significantly higher in early-onset type 2 diabetic group than those in the control group and in the late-onset type 2 diabetic group (chi(2)=7.85, P=0.005; chi(2)=8.81, P=0.003). The frequencies of Thr45 allele in the early-onset type 2 diabetic group were significantly different from those of the control group (13.4% vs 5.2%, chi(2)=7.15, P=0.008) and the late-onset type 2 diabetic group (13.4% vs 5.8%, chi(2)=8.13, P=0.004). The presence of Thr45 allele was shown to have an association with early-onset type 2 diabetes (OR=2.52, 95% CI: 1.42-4.49). Furthermore, the subjects carrying the variant appeared to have lower serum concentration of C-peptide in diabetic group. However, the frequencies of polymorphism genotypes of Neuro D gene showed no difference between the late-onset type 2 diabetic group and the control group.</p><p><b>CONCLUSION</b>The genetic polymorphism in the Neuro D is associated with the development of early-onset type 2 diabetes. The presence of Thr45 allele may represent a risk factor for early-onset type 2 diabetes among Chinese.</p>