The power of generalized odds ratio in assessing association in genetic studies with known mode of inheritance
The generalized odds ratio (OR<sub>G</sub>) is a novel model-free approach to test the association in genetic studies by estimating the overall risk effect based on the complete genotype distribution. However, the power of OR<sub>G</sub> has not been explored and, particularly, in a setting where the mode of inheritance is known. A population genetics model was simulated in order to define the mode of inheritance of a pertinent gene--disease association in advance. Then, the power of OR<sub>G</sub> was explored based on this model and compared with the chi-square test for trend. The model considered bi- and tri-allelic gene--disease associations, and deviations from the Hardy--Weinberg equilibrium (HWE). The simulations showed that bi- and tri-allelic variants have the same pattern of power results. The power of OR<sub>G</sub> increases with increase in the frequency of mutant allele and the coefficient of selection and, of course, the degree of dominance of the mutant allele. The deviation from HWE has a considerable impact on power only for small values of the above parameters. The OR<sub>G</sub> showed superiority in power compared with the chi-square test for trend when there is deviation from HWE; otherwise, the pattern of results was similar in both the approaches.
