Heterogeneity in the map distance between X-linked agammaglobulinemia and a map of nine RFLP loci.

In nine family pedigrees in which X-linked agammaglobulinemia (XLA) is segregating, a multi-point linkage analysis has been carried out. In each family, the map distance, d, between XLA and a fixed point in a known map of nine RFLP loci on the X chromosome was estimated by calculating the log likelihoods, L(d). Using a new method, the 10-point likelihood was approximated by appropriately combining three 4-point likelihoods. Homogeneity tests (admixture tests) were performed showing clear evidence for heterogeneity of XLA.