The Variance for the Disequilibrium Coefficient in the Individual Hardy–Weinberg Test

It is of interest to detect the deviation from Hardy-Weinberg proportion (HWP) for a particular heterozygote. Hernández and Weir (1989, Biometrics 45, 53-70) suggested a disequilibrium coefficient approach and proposed a 1-d.f. chi2 test. This note derives the appropriate variance under the null hypothesis for performing this individual HWP test. Examples of applying the test to human genetic disease data are presented.