Standardizing a Composite Measure of Linkage Disequilibrium

The maximum and minimum are obtained for a composite measure of linkage disequilibrium used with genotypic data when the phase of double heterozygotes cannot be determined. These bounds are used to standardize the composite measure in the same way used for D′, the standardized gametic measure of linkage disequilibrium. Standardization produces a measure which lies between −1 and 1, and allows comparison of linkage disequilibrium between populations. The method is illustrated using two loci in the CASR gene.