Clinical implications include mechanism- and phenotype-aligned care: titrated fluids and vasoactives for limited cardiac or renal reserve; PK/PD optimization and timely antimicrobial de-escalation in obesity and chronic kidney disease; and immune/organ monitoring (e.g., monocyte HLA-DR, NGAL/KIM-1). The gene discussed is HAVCR1; the disease is obesity due to melanocortin 4 receptor deficiency.