The hazard imposed by low serum albumin status was only manifested in patients presenting at hospitalization with either a normal BMI (AdjHR 1.73, 95% CI 1.50–1.99, p < 0.001), overweight (AdjHR 1.55, 95% CI 1.35–1.79, p < 0.001), or class 1 obesity (AdjHR 1.37, 95% CI 1.12–1.68, p = 0.002)—but not with underweight (AdjHR 0.84, 95% CI 0.35–2.00, p = 0.698), class 2 obesity (AdjHR 1.17, 95% CI 0.77–1.75, p = 0.465), or class 3 obesity (AdjHR 1.70, 95% CI 0.84–3.42, p = 0.137) (Supplemental Tables S9 and S10, and Figure 2). The gene discussed is ALB; the disease is obesity due to melanocortin 4 receptor deficiency.