Association of Mitochondrial HVS-I Region Variants with Type 2 Diabetes in Pakistani Diabetic Subjects

OBJECTIVE: To analyse mitochondrial hypervariable segment I (HVS-I) variations in Pakistani type 2 diabetic subjects. STUDY DESIGN: Case-control study. Place and Duration of the Study: National Institute of Diabetes and Endocrinology, Dow University of Health Sciences, Karachi, Pakistan, between January 2019 to January 2021. METHODOLOGY: DNA from whole blood was isolated, and mitochondrial HVS-I region (16024-16370) of 92 individuals, including 47 controls and 45 diabetics, was amplified, sequenced, and analysed. RESULTS: Ninety-two variable sites in the sequenced region were identified and individuals were classified into 56 different haplotypes according to phylotree 17.0 classifications, where major haplotype M5 was nearly 2-fold higher in diabetes. Fischer's exact test revealed variant 16189T>C significantly associated with diabetes (Odds ratio = 12.9, 95% CI = 0.6917 - 2400248) as compared to controls. The authors further analysed 1000 Genomes Project data of Pakistani Control subjects (i.e. PJL, n=96) and found that besides 16189T>C (Odds ratio = 5.875, 95% CI = 1.093 - 31.57, p <0.0339), 16264C>T (Odds ratio = 16, 95% CI = 0.8026 - 314.7, p <0.0310) also showed significant association with diabetic subjects. Comparing diabetic subject data with global control population data of the 1000 Genomes Project, significant associations of eight variants in the studied region were found. CONCLUSION: Based on the results of this case-control study, it can be concluded that specific variations in the mitochondrial hypervariable segment I (HVS-I) region are significantly associated with type 2 diabetes in the Pakistani population. The major haplotype M5 was found to be higher in diabetic subjects and variants 16189T>C and 16264C>T were significantly associated with diabetes. These findings suggest that mitochondrial DNA variations may play a role in the development of type 2 diabetes in the Pakistani population.