Genetic Epidemiology of Complex Traits


Genetic epidemiology is a research discipline, which evaluates the contribution of genetic factors to disease incidence, prevalence, diagnosis, prevention and treatment, in the population. As most traits and diseases are influenced by a number of genetic and nongenetic factors, the identification and characterization of these factors using population‐based studies are difficult. The complex, multifactorial and context‐dependent pathophysiological basis of most traits and diseases is further compounded by a number of issues associated with the genetic structure of human populations. Genetic epidemiologists perform ‘assays’ investigating aspects of genetic population structure and thereby deal with these issues in coherent and compelling ways.

Keywords: polygenic traits; epistasis; linkage; genetic association; penetrance

Figure 1.

Representation of the coinheritance (i.e. genetic transmission) of a disease‐causing mutation or genetic variant and surrounding ‘founder’ chromosomal material over a number of generations. Homologous chromosomes are depicted by solid vertical lines. The numbers represent repeat lengths (alleles) associated with a microsatellite locus. The letters designate bases (alleles) at three single‐nucleotide polymorphic loci adjacent to the microsatellite locus. The circled ‘G’ base is a dominant and fully penetrant disease causing mutation. The arrows identify sites where recombination has occurred. In generation 1, two individuals produced 4 offspring and two that received the disease mutation (i.e. the inner two offspring). One of these offspring did not receive the entire chromosomal segment or ‘haplotype’ (123‐C‐G‐T) associated with the parent introducing the mutation into the population due to a recombination event which shuffled the 126 allele at the microsatellite locus with the C‐G‐T subhaplotype. The individuals possessing the mutation produce their own offspring and these offspring produce subsequent lines of descent (denoted by the dashed lines). Two descendants of these individuals (in generation N−1) mate with others and produce two offspring each. The two offspring from both matings receive the disease mutation, G. Note, that all the diseased individuals share the basic core C–G–T haplotype, but in the first mating the repeat allele 126 is coinherited with this haplotype while the repeat allele 123 is coinherited with this haplotype in the second mating.



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Rana, Brinda K, and Schork, Nicholas J(Jul 2007) Genetic Epidemiology of Complex Traits. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0005412.pub2]