In Swedish families with hereditary prostate cancer, linkage to the HPC1 locus on chromosome 1q24-25 is restricted to families with early-onset prostate cancer.

Prostate cancer clusters in some families, and an estimated 5%-10% of all cases are estimated to result from inheritance of prostate cancer-susceptibility genes. We previously reported evidence of linkage to the 1q24-25 region (HPC1) in 91 North American and Swedish families each with multiple cases of prostate cancer (Smith et al. 1996). In the present report we analyze 40 (12 original and 28 newly identified) Swedish families with hereditary prostate cancer (HPC) that, on the basis of 40 markers spanning a 25-cM interval within 1q24-25, have evidence of linkage. In the complete set of families, a maximum two-point LOD score of 1.10 was observed at D1S413 (at a recombination fraction [theta] of.1), with a maximum NPL (nonparametric linkage) Z score of 1.64 at D1S202 (P=.05). The evidence of linkage to this region originated almost exclusively from the subset of 12 early-onset (age <65 years) families, which yielded a maximum LOD score of 2.38 at D1S413 (straight theta=0) and an NPL Z score of 1.95 at D1S422 (P=.03). Estimates from heterogeneity tests suggest that, within Sweden, as many as 50% of early-onset families had evidence of linkage to the HPC1 region. These results are consistent with the hypothesis of linkage to HPC1 in a subset of families with prostate cancer, particularly those with an early age at diagnosis.