This is an exploratory method of study in which the genome is saturated with single nucleotide polymorphisms (SNPs). Researchers study association between these variants and the trait of interest (such as, cannabis use disorders). ‘GWAS’ are most commonly conducted by comparing cases (affected individuals) and controls (unaffected individuals) who are unrelated to each other. Family-based approaches can also be used. Rapid advances in technology have produced high density SNP chips (e.g. with one-million SNPs) that provide comprehensive coverage along the whole genome but coverage of specific genes may be less adequate. We are not aware of any GWAS of cannabis use disorders, although this design presents an avenue for progress.
