Ethnicity, body mass, and genome-wide data

Area of Science:

• Social Epidemiology
• Genetic Epidemiology
• Population Genetics

Background:

• Self-reported ethnicity is often used as a proxy for population substructure in epidemiological studies.
• Observed differences in health outcomes, such as body mass index (BMI), across ethnic groups may be influenced by genetic factors.
• Understanding the interplay between genetic ancestry and self-identified ethnicity is crucial for accurate epidemiological research.

Purpose of the Study:

• To investigate the influence of self-reported ethnicity on body mass index (BMI) in adolescents and young adults.
• To utilize genetic data to characterize population ancestry and assess its association with BMI.
• To determine if genetic ancestry explains the observed ethnic differences in BMI.

Main Methods:

• Employed a combined social and genetic epidemiology approach.
• Analyzed genetic information from over 5,000 single nucleotide polymorphisms (SNPs).
• Utilized principal components analysis (PCA) to infer population ancestry and control for genetic stratification.

Main Results:

• Significant differences in BMI and genetic principal components were observed between non-Hispanic white and Mexican-American respondents.
• The first principal component, reflecting population ancestry, was positively associated with BMI and explained approximately 3% of the genetic variance.
• Ethnic differences in BMI persisted even after statistically controlling for the genetic principal component.

Conclusions:

• Self-identified ethnicity remains a significant predictor of BMI in adolescents and young adults, independent of genetic ancestry.
• The developed method offers a way to adjust for genetic differences when examining ethnic disparities in health outcomes.
• Genetic background does not account for the observed influence of self-identified ethnicity on BMI in this sample.