The diagnostic value of cathepsin Z mRNA in the osteoporosis patients that had experienced a previous fracture was even stronger than for the entire osteoporosis group (Fig. 4d) (AUC, 0.96; sensitivity 100%, 95% CI 73.5 to 100%; specificity, 94.1%, 95% CI 71.3 to 99.9%). The gene discussed is CTSZ; the disease is osteoporosis.