Often an apparently homogenous population group contains subgroups that are genetically distinct. These subgroups may have allele frequency differences due to systematic ancestry differences. Such population structure is known as population stratification.
The mixture of groups of individuals with different allele frequency, i.e., heterogeneous genetic backgrounds, undermines the reliability of association testing results. The assumption of population homogeneity in association studies may not always be true, and violation of the assumption can result in statistical errors. Genetically distinct population subgroups, possibly resulted from interbreeding of two different population groups, can exhibit disequilibrium between pairs of unlinked loci which may create confounding or spurious associations. Therefore, it becomes important to find and quantify genetically distinct subgroups within a population group. Various techniques including principal component...
References and Readings
- Tiwari, H. K., Barnholtz-Sloan, J., Wineinger, N., Padilla, M. A., Vaughan, L. K., & Allison, D. B. (2008). Review and evaluation of methods correcting for population stratification with a focus on underlying statistical principles. Human Heredity, 66, 67–86. doi:10.1159/000119107.PubMedCrossRefGoogle Scholar