Study of inheritance of diabetes mellitus in Western Indian population by pedigree analysis.

ABSTRACT

OBJECTIVES: To study the inheritance pattern of diabetes mellitus in Western Indian population by analysing the pedigree of diabetes patients. METHODS: 3,921 individuals from 300 families were interviewed for family history in this study, out of which 770 were diabetic individuals. Statistical analysis of the data was carried out using T-test and Chi-square test. RESULTS: 37% cases of Type 1 DM and 58% cases of Type 2 DM showed family history of the disease. Of the cases showing family history for diabetes, 92% in case of Type 1 DM and 59% in case of Type 2 DM showed family history of Type 2 DM with a decrease in age of onset in the successive generations. Both the parents, when diabetic conferred equal risk of inheriting diabetes in offspring. The sex ratio of offspring suffering from diabetes was not influenced when only one of the parents was diabetic. However it was observed that the male offspring were highly susceptible when both parents were diabetic (Chi-square value=4.55 with 1 d.f.). The age of onset of diabetes did not show significant correlation with whether one or both the parents were diabetic. However, it was noteworthy that in case of familial history of diabetes there was a decrease in the age of onset in successive generations. CONCLUSION: This study suggests that family history of diabetes results in predisposition to early onset of the disease in successive generations and a cluster of genes involved in Type 2 DM may show a parental effect for predisposition to Type 1 DM in the offspring in this set of Indian population.