Adult nontwin sib concordance rates for type 2 diabetes, hypertension and metabolic syndrome among Asian Indians: The Indian Atherosclerosis Research Study

Jayashree Shanker¹, Saikat Kanjilal³, Veena S Rao², Ganapathy Perumal¹, Natesha B Khadrinarasimhiah², Manjari Mukherjee⁴, Shamanna S Iyengar³, Vijay V Kakkar⁵

¹Mary and Garry Weston Functional Genomics Unit, Thrombosis Research Institute, Bangalore, India; ²Tata Proteomics and Coagulation Unit, Thrombosis Research Institute, Bangalore, India; ³Cardiology Division, St. Johns’ Medical College and Hospital, Bangalore, India; ⁴University Department of Chemical Technology, Mumbai, India; ⁵Founder Chairman, Thrombosis Research Institute-London, UK

Abstract: Diabetes (DM), hypertension (HTN), and metabolic syndrome (MS) are established cardiovascular risk factors with a complex etiology. The aim of the present study was to estimate the rates of concordance for the above coronary risk factors between siblings in Asian Indian families with premature coronary artery disease (CAD). Spouse concordance rates were used to evaluate the relative contribution of shared genes and lifestyle towards these traits. A total of 508 families comprising of 1250 sib-pairs and 463 corresponding spouse-pairs were analyzed. Concordance rates were manually determined. Plasma lipids were estimated by standard enzymatic assay. The concordance rates among sib-pairs for DM, HTN, and MS was 11% (N = 136), 14% (N = 174), and 23% (N = 287), while the corresponding concordance for spouse-pairs was 2.8% (N = 13), 6.3% (N = 29), and 28.1% (N = 130), respectively. Employing Chi-square test, sib-pairs showed significantly higher concordance for diabetes (p < 0.0001) and hypertension (p 0.0001) while spouse-pairs had higher concordance for metabolic syndrome (p = 0.033) in our study. These findings suggest a probable dominant genetic component in the causation of DM and HTN and a predominantly nongenetic component for metabolic syndrome among Asian Indians.

Keywords: sib-pairs, spouse-pairs, type 2 diabetes, hypertension, metabolic syndrome, concordance, CAD, Asian Indians