Linkage of aggressive prostate cancer to chromosome 7q31-33 in German prostate cancer families

It has been suggested that chromosome 7q32 contains genes that influence the progression of prostate cancer from latent to invasive disease. In an attempt to confirm this linkage to prostate cancer aggressiveness, 100 German prostate cancer families were genotyped using a panel of eight polymorphic markers on chromosome 7q. We used a multipoint allele sharing method based upon a likelihood ratio test implemented in GENEHUNTERPLUS v1.2 in order to calculate the nonparametric Z_Ir and the associated LOD scores. We applied the aggressiveness of prostate cancer given by the pathological tumour grade of each individual, and the mean age of onset of a family as covariates, and constructed two weighted models. The first (weight_0-1 model) puts weights on families with at least two cases of GIII prostate cancer. The second (weight_0-2 model) also adds weights to families with early and late onset cancer respectively. The unweighted analysis gave no evidence of linkage to chromosome 7q. The Z_Ir scores increased when including the covariates, to 2.60 (P=0.005) using the weight_0-1 and to 3.02 (P=0.001) using the weight_0-2 model for late onset prostate cancer. The associated LOD scores were respectively 1.47 (P=0.009) and 1.98 (P=0.002). The markers that gave most evidence for linkage were exactly in the range of the published prostate cancer aggressiveness region. Our results support a widespread relevance of this locus and suggest that aggressive and late onset prostate cancer is linked to chromosme 7q31-33 in the German population.