Backgrounds Body surface area (BSA) is an important trait used for many clinical purposes and is associated with a variety of diseases including cardiovascular diseases and cancer. People's BSA may vary due to genetic background, race, and different lifestyle factors (such as walking, exercise, reading, smoking, transportation, etc.). Genome-wide association study of BSA was conducted on 5,336 subjects of four ethnic populations of European-American, African-American, Hispanic-American, and Chinese-American from MESA (The Multi-Ethnic Study of Atherocloris) data using unconditional and conditional full genetic models for analyzing genetic effects of additive, dominance, epistasis, and genetic by ethnicity interactions.
Results Conditional association analyses revealed that lifestyle cofactors could affect the genetic effects of genes that regulate BSA. Moreover, impacts of the lifestyle cofactors on BSA could depend on the genotypes of several SNPs, and ethnicity of individuals. In this study, fifteen SNPs were identified with highly significant (Experiment-wise PEW < 1×10–5) genetic effects using unconditional full genetic model, of which thirteen SNPs had individual genetic effects and seven SNPs were involved in four pairs of epistasis interactions. Seven single SNPs and eight pairs of epistasis SNPs were additionally identified using exercise, smoking, and transportation cofactor-conditional models. Estimated heritabily was 72.88% using unconditional model and 74.85 ~ 79.87% using lifestyle cofactor-conditional models. It was revealed that lifestyle cofactors could contribute, suppress, increase or decrease the genetic effects of BSA associated genes. From gene ontology analysis, it was observed that several genes are related to the metabolic pathway of calcium compounds, a main compound in several diseases related to obesity, coronary artery disease, type-2 Diabetes, Alzheimer disease, childhood obesity, sleeping duration, Parkinson disease, and cancer.
Conclusions In summary, our study provides novel insights into the genetic mechanism of BSA in MESA population, and influences of different lifestyle cofactors on the genetic effects of BSA associated loci.