Molecular Characterization of Insulin Gene in Diabetic Foot Ulcer Patients: A Pilot Study from Bengal Bay Coastal Origin

Objective: Many studies have showed that foot ulcer is the most frequent occurrence among diabetic patients in the south Indian origin. This study aimed to investigate on the hypothesis that in patients with diabetic foot ulcer in south Indian subjects there is a substitution within nucleotide sequence of coding region related to insulin gene and this may be signifying a link disequilibrium with the class III allele in the insulin gene locus, which can be considered due to its relevance with diabetes. We aim to examine this part of insulin gene to find out if there is any mutation within the insulin gene sequence that is relevant with diabetes mellitus. Materials and Methods: We used the PCR products of the amplified insulin gene from 40 patients diagnosed with foot ulcer seeking mutations, which might be in association with the class III allele and therefore indicates its relevance with the manifestation of diabetic foot ulcers. Results: We identified a β-chain mutant (i.e. insulin Chicago) using the restriction enzyme (MboII) in individuals afflicted with foot ulcer. A couple of patterns (α and β) were found indicating the presence of PstI polymorphism within the 3' un-translated part of the insulin gene. Besides, allele frequencies in subjects homozygous for α allele, homozygous for β allele and heterozygous were respectively 0.3 (12/40), 0.125 (5/40) and 0.575 (23/40). No significant variant regarding allelic frequency was characterized between the patients and normal controls, though a mutation in B-chain (insulin Chicago) was observed. Conclusion: Despite linkage disequilibrium between this polymorphism in the 3' un-translated portion of the insulin gene and the class III allele, it is unlikely to have advantage than the class III allele itself on prognosticating diabetes.