MTNR1B gene polymorphisms and susceptibility to Type 2 Diabetes: A pilot study in South Indians

• First study to address MTNR1B gene SNPs with Type 2 Diabetes in South Indians
• Haplotype distribution suggests contribution of MTNR1B gene to the disease.
• Reinforces the role of non-coding SNPs of MTNR1B in the development of the disease

Type 2 Diabetes (T2D) is the major health concern in the Indian subcontinent. A genome-wide association study carried out with non-diabetic Indians showed association of MTNR1B variants with fasting glucose. MTNR1B mediates the effect of melatonin on insulin secretion. In light of the growing importance of MTNR1B in the etiology of T2D, we sought to test its association with the disease in the south Indian type 2 diabetics. Five single nucleotide polymorphisms of MTNR1B (rs10830962, rs10830963, rs3847554, rs1387153 and rs2166706) were genotyped in 346 T2D patients and 341 non-diabetic controls. None of the SNPs differed significantly between patients and controls with respect to allele and genotype frequencies. Linear regression analysis after adjustment for age, sex and BMI showed a significant positive association of rs3847554 with fasting glucose under recessive model (β = 14.98, p = 0.012). Haplotypes constituted by minor alleles of rs3847554, rs1387153, rs2166706, rs10830963 and major allele of rs10830962 showed significant positive correlation with fasting glucose (p < 0.05). Though the results obtained are suggestive of MTNR1B role in T2D etiology, they need to be confirmed with much larger sample sizes.