Research questions
1. What is the genetic basis of body composition in the South Asian population and how does it differ from other populations?
2. How does the genetics of body composition affect the biomarkers related to metabolic traits?
Rationale
Body composition studies have found that South Asians have lower lean mass and higher body fat percentage at similar or lower levels of BMI when compared to populations with European ancestry. This phenomenon is described as the ‘Y-Y paradox’ or ‘The thin fat phenotype’ and was postulated to explain the higher risk of diabetes mellitus in South Asians. South Asians are characterized by higher body fat percentage, truncal adiposity, and subcutaneous adipose tissue, particularly in the deeper depots of the abdominal region. A meta-analysis of imaging studies that compared various fat compartments between South Asian and European ancestry populations found that South Asians had higher abdominal subcutaneous adipose tissue and similar visceral adipose tissue volume, albeit at a lower BMI (This means at similar BMI, visceral adipose tissue volume is indeed higher in South Asians).
Given that differences in body composition are seen in South Asians across different studies, including migrant populations, it is reasonable to assume it is at least partly genetically determined. We propose to study the genetics of body composition as measured by anthropometry, bioimpedance and imaging and its relation to blood biomarkers related to metabolic traits in the South Asian population through GWAS studies.