Results ANALYSIS OF PKD 1 RECOMBINANTS One hundred and ninety two informative

arm of chromosome 16,1 many linkage studies have been performed on ADPKD kindreds. The gene present in chromosomal region 16pl 3.3 has been designated PKD 1. Genetic heterogeneity has now been confirmed with the demonstration that ADPKD families unlinked to 16pl 3.3 (PKD2) show linkage to markers on chromosome 4q.2 Two recent studies estimate the proportion of PKD1 out of all ADPKD linked families to be 0O813 and 0-86,4 although the confidence limits were wide in both studies. In order to facilitate accurate genetic mapping ofPKD 1, markers have been isolated from the short arm of chromosome 16. These have been ordered with respect to each other by a combination of linkage analysis, physical mapping to human-rodent hybrids, and long range restriction mapping,5-9 and are summarised in fig 1. All the probes used by Reeders et al' lie in the region 1 6p 13.11-1 6pter. Genetic link-