A case control association study of COMT gene polymorphism (I/D) with type 2 diabetes and its related factors in Pakistani Punjabi population

BACKGROUND The Catechol-O-Methyl Transferase (COMT) gene polymorphism (I/D of C nucleotide at base position 900) has been previously implicated in the development of type 2 diabetes (T2D) and kidney disease. So, aim of this study was to find association of I/D polymorphism with T2D, and its associated factors like family history and nephropathy (End Stage Renal Disease, ESRD) patients in a cohort of Pakistani Punjabis. METHODS Genomic DNA was extracted from human subjects divided as four study groups: controls (n = 46), diabetics (n = 46), diabetics with nephropathy/ESRD (n = 53), and non-diabetics without nephropathy/ESRD (n = 43). The 900 I/D C polymorphism in the COMT gene was tested by PCR-RFLP method. Genotype and allele frequencies as well as Odds Ratios were calculated for these groups. Groups were compared statistically for the analysis of genotypes, alleles, biochemical parameters as well as disease status. RESULTS In comparison with control group (non-diabetic, non-nephropathy), there was no significant difference in rest of the three groups for allele or genotype frequencies of COMT gene. However, Chi square (χ(2)) analysis identified a significant (p = 0.02) correlation of the 900 I/D C polymorphism with family history of diabetes, as it was found that greater number (74%) of patients having I allele had a positive family history of T2D. CONCLUSIONS A significant correlation of the COMT polymorphism (900 I/D C) with the family history of T2D has been observed, which has not been previously reported in Pakistani Punjabi population, however, this preliminary finding requires further validation studies.