KLK3 and early-onset autosomal dominant Alzheimer disease: Consider cancer or Alzheimer’s disease, for example—both of these debilitating diseases have precise biomarkers and distinct biological boundaries defining the onset, progression, and severity of the disease, such as prostate-specific antigen and beta-amyloid (and/or tau) plaques (Alzheimer’s disease), and undergo comprehensive screening via imaging [12,13,14].