The 4Kscore test combines total PSA, fPSA, intact PSA, and human kallikrein-related peptidase 2 (hK2), along with clinical information such as age, digital rectal exam (DRE) results, and history of prior negative biopsy, to predict the likelihood of high-grade PC (Gleason score ≥ 7). The gene discussed is KLK3; the disease is pachyonychia congenita.