Statistical Analysis of Genetic Association Study Results
Genetic association studies examine relationships between the presence of a genotype and a phenotype. Under this general aim, there are several nuances: the genotype may in fact be several genotypes acting jointly; the relationship may only be applicable to a subset of the disease (especially in heterogeneous diseases such as asthma or depression); or the relationship may be apparent only in the presence of another factor. Correlation does not mean causation, and as the aim is to find causality, some assessment of potential causality should ideally be carried out. In this chapter, standard association analysis will be reviewed, followed by discussion of more advanced approaches to association analysis. The latter half of the chapter is devoted to GWAS analysis, which has unique features and quality control steps.