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. Author manuscript; available in PMC: 2014 Oct 18.
Published in final edited form as: Curr Protoc Hum Genet. 2013 Oct 18;79:6.13.1–6.13.19. doi: 10.1002/0471142905.hg0613s79

Figure 4. Di Finetti Diagram.

Figure 4

A de Finetti diagram is used to graph genotype frequencies in populations. It presumes two alleles, and can be used to plot genotype frequencies at which Hardy-Weinberg Equilibrium (HWE) is satisfied. The figure shows a rectangular prism with surfaces plotted in its interior. The vertices of the triangles on the ends of the prism correspond to genotypes as shown: AA, AB and BB. The length of the prism is a scale of individuals in the population from 1 (far left) to ≥ 400 (far right). The area between the upper and lower internal plot surfaces define the combinations of genotypes that are consistent with HWE given a particular population size. As the population size increases, an increasingly small proportion of all of the possible genotype combinations are in HWE. However, difference between the in-HWE and out-of-HWE regions changes increasingly gradually as the population size reaches hundreds of individuals. For this reason, a data set of 100's of individuals allows stringent criteria to be used in assessing whether a set of genotypes is out of HWE—potentially due to misalignment.