Objective: To evaluate the role of polymorphism in the neurogenic differentiation factor 1(Neuro D) gene in Chinese patients with type 2 diabetes mellitus.
Methods: 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.
Results: 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.
Conclusion: 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.