Genetic Data Concepts and Tests

Abstract

This chapter provides an overview of two important concepts relevant to population-based association studies: linkage disequilibrium (LD) and Hardy- Weinberg equilibrium (HWE). Both of these concepts are based on the genetic component of our data and do not involve the trait that we aim to associate with this genetic information. Instead, consideration of LD and HWE is an important step of data processing that typically precedes consideration of association, and thus a discussion is included in this text. Both LD and HWE are measures of allelic association|the difference between them is that LD is a measure of allelic association between two sites on the genome, while HWE is a measure of allelic association between two homologous chromosomes at a single site.