Probable loose linkage between the ABO locus and Waardenburg syndrome type I.

The possibility of linkage was tested in 3 large kindreds with Waardenburg syndrome type I against the ABO locus. Loose linkage is probably present; the recombination fraction in males, females, and both sexes combined seems to be approximately theta' equals 0.175, theta equals 0.255, and theta', theta equals 0.20, respectively. There are still more informative matings to be studied in those pedigrees, as well as the inminent possibility of determining the phase status in several of them, for the ABO locus and a few other loci.