The test characteristics for the PSA test in detecting prostate cancer are comparable to those for mammography for breast cancer screening, with a sensitivity of 72% and a specificity of 30%–35% at a test threshold of 4 ng/mL.2 However, a lower threshold of 3 ng/mL adopted in Sweden recently has led to increased sensitivity at the expense of reduced specificity. The gene discussed is KLK3; the disease is prostate cancer.