In genetic epidemiology, family studies are studies of whether a disease or trait "runs in a family". In other words, they are studies aimed at detecting the presence or absence of familial aggregation for the disease or trait, in which having a family history is associated with greater risk. The family research design can also be used to estimate penetrance for a given genotype, to conduct genetic association studies, and to study potential modifiers of an individual's genetic risk.[1][2] If a family study shows that a trait is familial, this is a necessary, but not sufficient, criterion for it to be established as genetically influenced.[3]
Types
There are three main types of family studies in genetics:
- Those aimed at measuring the extent of familial aggregation for a trait
- Familial aggregation is the practice of combing multiple data sets of different traits and/or characteristics in a family. [4]
- Family history of disease is collected in case studies, which seeks if a certain disease of one family member increases the risk of that disease being passed down to others. This could be related to either genes or environmental factors.[5]
- Linkage studies aimed at identifying specific genetic loci that have a moderate to large effect on risk
- Association studies aimed at detecting loci with relatively small effects on risk.[8]