Associations of genetic scores for birth weight with newborn size and later anthropometric traits and cardiometabolic risk markers in South Asians

We recently reported genetic variants associated with birth weight and their effect on future cardiometabolic risk in Europeans. Despite a higher burden of low birth weight and cardiometabolic disorders, such studies are lacking in South Asians. We generated fetal and maternal genetic scores (fGS and mGS) from 196 birth weight-associated variants identified in Europeans and conducted association analysis with various birth measures and serially measured anthropometric and cardiometabolic traits from seven Indian and Bangladeshi cohorts. Although fGS and mGS were comparable to Europeans, birth weight was substantially smaller suggesting strong environmental constraints on fetal growth in South Asians. Birth weight increased by 50.7g and 33.6g per standard deviation fGS (P=9.1x10-11) and mGS (P=0.003) in South Asians. The fGS was further associated with childhood body size and head circumference, fasting glucose, and triglycerides in adults (P<0.01). Our study supports a common genetic mechanism partly explaining associations between early development and later cardiometabolic health in different populations, despite phenotypic and environmental differences.