Blood samples undergo DNA extraction and are then genotyped. Genotyping of the first 34,000 participants’ blood samples used a custom Infinium Multi-Ethnic Global Array SNP chip (MEGA, Illumina, Inc.). Genotyping of all other participants’ samples uses whole exome sequencing and/or a custom chip.
As of December 2021, the first 34,000 samples have undergone genotyping. Genotyping provides four types of genetic information:
(1) pharmacogenetic (PGx) information describing variations in genes that may impact how a medication works in the body (for example, clopidogrel);
(2) variations in genes, which are known to or expected to confer disease risk;
(3) genetic variations that identify participants as being a “carrier” of a disease (like cystic fibrosis) and
(4) genetic variations that occur throughout the genome that can be useful for studying the genetic underpinnings of health and disease.
The first three types of genetic information could yield results that are clinically meaningful and may be returned to the participant, while the fourth is the foundation of research into the genetic contributions to health and disease.