Glycoproteins such as carbohydrate antigen 19-9 (CA19-9), CA125, prostate-specific antigen (PSA), and alpha-fetoprotein (AFP-L3) are used as cancer biomarkers in clinical practice, and detection of core-type fucosylated or multi-sialylated LacdiNAc structures on PSA has the potential to improve diagnostic or prognostic performance [14,15]. The gene discussed is KLK3; the disease is cancer.