Different criteria for routine or targeted post-LT PCP prophylaxis are based on adult incidence rate ≥ 3.5%, anytime total lymphocyte count < 400 cells/μL, anti-rejection immunosuppressant use, till prednisolone dose < 10 mg/day, or the presence of 2 or more of the following risk factors: pretransplant renal failure, fulminant hepatic failure, retransplantation, intraoperative Roux-loop-hepaticojejunostomy, post-LT intensive care unit stay > 5 days, renal failure, albumin-creatinine ratio, and total parenteral nutrition > 48 h. The gene discussed is ALB; the disease is pneumocystosis.