This also occurred in medical diagnostics, where clinical tests are performed to determine which disease or condition better explains patient’s symptoms and signs, such as the test to measure the prostate-specific antigen (PSA) level [63], or the genetic test to identify cystic fibrosis [41], or cellular analysis to detect cell-based diseases such sickle anemia [3], or tests based on medical imaging to ascertain or rule out the presence of breast cancer [59]. Here, KLK3 is linked to breast cancer.