Table 1.
Definition of Terms
| Term | Definition |
|---|---|
| High-penetrance cancer susceptibility syndrome | A cancer predisposition syndrome wherein a mutation in the implicated gene produces a phenotype in a high proportion of individuals who carry the mutation |
| SNP | A variation in DNA sequence where a single nucleotide is replaced by another; SNPs are thought to represent the most common form of genetic variation in the genome |
| Clinical validity | The accuracy with which a genetic test can identify or predict the presence or absence of a particular clinical condition taking into account the specificity, sensitivity as well as the penetrance of the genetic variation |
| Clinical utility | The degree to which the use of a test informs clinical decision making and leads to improved health outcomes |
| Candidate gene studies | A study that identifies genetic associations by assessing genetic variants that are suspected of being involved in the expression of a particular trait or disease |
| GWAS | A systematic hypothesis-free search for genetic variations, in the form of SNPs, across the genome to identify genetic associations with a disease or trait |
| Minor allele frequency | Frequency of the less common allele of a polymorphic locus |
| Risk allele | Any one of several variants of a gene that occupy the same position locus on a chromosome and is associated with risk of a particular trait or disease |
| Linkage disequilibrium | The non-random association of alleles of different polymorphisms in a population |
| Population stratification | Genetic differences between cases and controls not due to the trait or disease being studied but rather due to sampling of populations with different ethnicities or ancestries; population stratification can lead to erroneous genetic associations |
| Genetic heterogeneity | Multiple genetic mutations can result in the same disease phenotype |
| Bonferroni correction | A multiple-comparison correction used when several statistical tests are being performed simultaneously; in GWAS, using the Bonferroni correction helps to avoid spurious genetic associations |
| Winner's curse | Results of GWAS may be subject to varying degrees of upward bias in effect size estimates due to having to pass through stringent statistical thresholds |
| Epistasis | Gene-to-gene interactions where the effects of one gene are modified by one or several other genes |
| PAR% | The reduction in incidence of a particular disease that would be observed if the population was entirely unexposed, compared with its actual exposure; in genetic epidemiology, combining knowledge of risk allele frequency and genotypic relative risk, the attributable fraction of cases that would not occur if no one in the population had the risk allele can be determined |
| FRR | The ratio of disease risk in biological relatives of affected individuals compared with disease risk in the general population; in general, the higher the FRR, the stronger the genetic effect |
| Publication bias | A type of reporting bias wherein statistically significant or positive results are more likely to be published |
Abbreviations: SNP, single nucleotide polymorphism; GWAS, genome-wide association studies; PAR, population attributable risk; FRR, familial relative risk.