Polymorphism of Telomerase Reverse Transcriptase (TERT) Gene Rs2853669 in Iraqi Patients with Type2 Diabetes Mellitus

Abstract

The aim of this study was to investigate the association of polymorphism of telomerase reverse transcriptase (TERT) rs2853669 to the susceptibility of type2 diabetes mellitus in Iraqi patients. Forty five patients with  type 2 diabetes mellitus (20 males and 25 females) and 35 healthy controls (17 males and 18 females) were genotyped for telomerase reverse transcriptase (TERT) rs2853669 using  TaqMan custom SNP genotyping assay .In both patients and control groups , the distribution frequencies of genotypes and alleles of the rs2853669 A/G gene were in Hardy-Weinberg equilibrium (p>0.05) . The most common genotype in both control and type2 diabetes mellitus patients was AG with a percentage of 91.12% and 74.28% respectively. The genotypes AG and AA were higher in type2 diabetes mellitus patients than healthy control 91.12% and 8.88% in patients vs. 74.28% and 22.85% in controls . A allele was more predominate comparing to G allele with percentage of 60% and 54.44% for A, 40% and 45.56% for G in control and patients groups respectively with no significant differences .

The association analysis of (TERT) rs2853669 with susceptibility to type2 diabetes mellitus showed that the individuals carrying the heterozygous AG genotype and homozygous AA genotypes were more likely to have a significantly increased risk of type2 diabetes mellitus with OR=3.5481 (CI95%0.9902 to 12.7128), and OR= 0.3293 (CI95% 0.0902 to 1.2020( respectively, p= 0.0518 and 0.0927 for each genotype respectively. The GG genotype decreases the association with type2 diabetes mellitus OR=0.2527 (CI95%0.0100 to 6.3964), p =0.4041. These results suggested that G allele might play a protective role against type2 diabetes mellitus whereas the A allele might consider a risk factor in type2 diabetes mellitus . The subgroup analysis revealed that  the type2 diabetes mellitus risk of females with (TERT) gene AG genotype was 2.6250 times higher than that in controls OR= 2.6250 (CI 95% 0.6155 to 11.1954), p= 0.1922 .  GG genotype decreases the probability of contracting the disease significantly with OR = 0.2288 (CI 95% 0.0088 to 5.9470), p = 0.3749. AA genotype decreases also the association with type 2 diabetes mellitus with OR= 0.4952 (CI95% 0.1121 to 2.1879), p = 0.3539 . Among males, the AG genotype increased type2 diabetes mellitus  risk among patients OR=9.8966 (CI95%0.4741 to 206.6018) p=0.1393. The homozygous AA genotype decreases the association with the disease OR=0.1010 (CI95%0.0048 to 2.1094) p=0.1393. There were no males with the homozygous genotype GG in patients and controls.