Phenome-wide association study


In genetic epidemiology, a phenome-wide association study, abbreviated PheWAS, is a study design in which the association between single-nucleotide polymorphisms and a large number of different phenotypes is statistically estimated. The aim of PheWAS studies is to examine many different phenotypes to see which, if any, are associated with a given genetic variant. It is a complementary approach to the genome-wide association study, or GWAS, methodology. A fundamental difference between the GWAS and PheWAS designs is in the direction of inference: in PheWASs, it is from exposure to outcome, the reverse of that used in GWASs. The approach has proven useful in rediscovering previously reported genotype-phenotype associations, as well as in identifying new ones.
The PheWAS approach was originally developed partly due to the widespread availability of anonymized electronic health record data. However, PheWASs have also been conducted using data from existing epidemiological studies. In 2010, a proof-of-concept PheWAS study was published based on EHR billing codes from a single study site. Though this study was generally underpowered, its results suggested the potential existence of new associations between multiple phenotypes, possibly due to a common underlying cause. As of 2016, this study is the oldest PheWAS in the EHR-linked eMERGE database. This paper also coined the abbreviation "PheWAS". As of 2019, PheWAS in the EHR has been conducted using ICD-9-CM, ICD-10, and ICD-10-CM diagnosis codes.