Abstract:

Objective To investigate the prevalence and clinical characteristics of Isl-1 gene mutations in early-onset type 2 diabetes mellitus in Shanghai. Methods Ninety-six patients with early-onset type 2 diabetes mellitus were enrolled. General data such as age, gender and blood pressure and laboratory data such as glucose and lipid metabolism were collected, and comparisons were made between groups. PCR-direct sequencing was employed to detect the Isl-1 gene mutations in two groups, loci of gene mutations, frequencies of genotype and allele were observed, and the clinical characteristics of mutation gene carriers were investigated. Another 100 healthy volunteers were served as normal controls. Results Compared with normal controls, patients with early-onset type 2 diabetes mellitus were younger, with significantly higher levels of fasting blood glucose, fasting insulin and triglyceride (P<0.05 or P<0.01). Though fasting C-peptide level in patients with early-onset type 2 diabetes mellitus was higher than that in normal controls, there was no significant difference between them (P>0.05). PCR-direct sequencing revealed that there were no Isl-1 gene mutations in normal controls, while E283D missense mutation (A→T) in exon 5 of Isl-1 gene was found in two patients with early-onset type 2 diabetes mellitus, with 1.0% for frequency of T allele and 2.1% for frequency of AT genotype. Fasting C-peptide levels of two mutation gene carriers were 0.6 ng/mL and 0.2 ng/mL, respectively, and were significantly lower than the lower normal limit (0.82 ng/mL) (P<0.05). Conclusion E283D mutation in exon 5 of Isl-1 gene can be screened from patients with early-onset type 2 diabetes mellitus in Shanghai, and fasting C-peptide levels of mutation gene carriers are lower than the lower normal limit.

Key words: early-onset type 2 diabetes mellitus, Isl-1 gene, mutation, fasting C-peptide