Estimation of linkage disequilibrium from conditional haplotype data: Application to β‐globin gene cluster in American blacks

Simple estimators of gene frequencies and linkage disequilibria are proposed when haplotype data are available from four parental chromosomes of a child (or fetus) for whom genetic counseling is sought for a disease condition. The method is illustrated with restriction site polymorphisms associated with sickle‐cell anemia (Hb‐β S ) gene as surveyed in genetic counseling data from American blacks. The method suggested here is shown to be useful in testing for the significance of interactions of site‐specific variations of any order in the chromosomal region assayed.