LINKAGE ANALYSIS OF CHROMOSOME 1Q MARKERS IN 136 PROSTATE-CANCER FAMILIES

Prostate cancer shows evidence of familial aggregation, particularly a t young ages at diagnosis, but the inherited basis of familial prostat e cancer is poorly understood. Smith et al. recently found evidence of linkage to markers on Iq, at a locus designated ''HPC1,'' in 91 famil ies with multiple cases of early-onset prostate cancer. Using both par ametric and nonparametric methods, we attempted to confirm this findin g, in 60 affected related pairs and in 76 families with three or more cases of prostate cancer, but we found no significant evidence of link age. The estimated proportion of linked families, under a standard aut osomal dominant model, was 4%, with an upper 95% confidence limit of 3 1%. We conclude that the HPC1 locus is responsible for only a minority of familial prostate cancer cases and that it is likely to be most im portant in families with at least four cases of the disease.