Before diving into this article, It is important to understand what SNPs (Single Nucleotide Polymorphisms are). If you need a refresher, see the article below:
GWAS stands for Genome Wide Association Study: these studies are observational studies of a set of genetic variants, genome-wide. The studies focus on the associations between SNPs and major human diseases.
So, what’s an observational study?
An observational study is a type of study where inferences are drawn from a sample population, where the independent variable is not under the control of the researcher. There are 3 major types of observational studies—
Case-control: This is when you have 2 existing groups with differing outcomes identified + they are compared on the basis of a causal attribute
Cross-sectional: This analyzes data from a population or subset at a specific point in time
Longitudinal: This is a correlational study that involves repeated observations of one variable over long periods of time. There are 2 types:
Cohort: This type of study samples a group of people with a defining characteristic, such as birth, and performs a cross section at intervals through time.
Panel: This kind of study analyzes two-dimensional panel data (for example: cross sectional and longitudinal)
GWAS studies usually investigate common diseases using case-control or cohort studies.
The first GWAS study was published in 2005 on Age-Related Macular Degeneration, a major cause of blindness in the elderly. Shortly after, in 2007, the Wellcome Trust Case Control Consortium (WTCCC) set the stage—they published Genome-wide association study of 14,000 cases of seven common diseases and 3,000 shared controls. This paper showed that large sample sizes, rigorous study design and multiple testing corrected significance level were and remain necessary for discovery.
Here is a link to my favorite dashboard that monitors the diversity of participants across all published GWAS. It is notable that the approx. 96% of the participants are of European descent. I think there is room for a push towards diversity and inclusion in this space.