The genetic linkage between the PKU locus and the loci for amylase 1, amylase 2, Fy, PGM 1, and Rh and the question of assignment of the PKU locus to chromosome no. 1.

The alpha-amylase loci Amy 1 and Amy 2 and other loci on chromosome 1 were investigated for their linkage relationship to the PKU locus. Ten families were informative for the study of linkage between PKU/Amy, 20 for PKU-Fy, 11 for PKU/PGM 1, and 10 for PKU/Rh linkage. The probabilities of linkage at different recombinant fractions were calculated according to Bayes' theorem. The results are in striking contrast with those of Kamaryt et al. who found strong evidence for close linkage between the amylase loci and the PKU locus, whereas with our results close linkage can be excluded; loose linkage is possible but unlikely. The results are discussed with regard to the genetic heterogeneity of phenylketonuria.