Alternatively, mutagenic changes occur in the cancer cell genome, which are irreversible and leave the cells susceptible to further treatment strategies (see below) such as (i) specific mutations within the AR gene to broaden the substrate choice for the receptor, (ii) amplification of the AR gene, as seen in up to 50% of prostate cancers, as either X chromosome aneuploidy or more commonly a tandem amplification of the AR locus (see Table 1). The gene discussed is AR; the disease is cancer.