Table 1.

Glossary of Common Terms Used in Genetic Studies

Term	Definition
Phenotype	Outcome variable of interest, such as case/control status or a quantitative measure of symptom severity
Genome	The entirety of hereditary information of an organism. Humans have approximately 3.2 billion base pairs of primarily nuclear DNA
Locus	A location in the genome, which might be one specific position, a region such as a gene, or a segment of DNA that contains genetic variants that are correlated with one another (a “haplotype”)
Allele	One of two or more alternative genetic variations at a particular locus
Genotype	For most genetic variants in the genome, humans have two copies of a genetic variant (given the 23 pairs of chromosomes of humans). The genotype of a person is the pair of alleles at a specific position in the genome
SNP	Single nucleotide polymorphism: a genetic variation indexed by a specific location in the genome and (typically) a name, which takes the form of an “rs number.” For example, rs10038727 in Wilker et al. is an SNP with two alleles, G and A. Thus, the three genotypes that an individual might have are GG, GA, and AA
Association	Genetics term for statistical relationship, which might be assessed by logistic or linear regression or similar methods
Exome	The portion of the genome that directly codes for proteins; collectively the exome accounts for 1.5% of the genome
Intronic	From the noun ”intron,” intronic denotes location in an intron of a gene
Intergenic	Refers to a location in the genome that is not within known protein-coding genes