Approximate variance for a standardized composite measure of linkage disequilibrium.

The approximate variance for the standardized measure of gametic linkage disequilibrium has been described. However, this approach assumes knowledge of the phase of double heterozygotes or Hardy-Weinberg equilibrium. Here we give the approximate variance for a composite measure of linkage disequilibrium which depends only on genotype frequencies. We show by simulation that this variance approximation is valid over a range of allele probabilities and departures from Hardy-Weinberg equilibrium.