Serum ADA levels increased proportionally with the severity of malnutrition as assessed by the Malnutrition Universal Screening Tool (MUST), rising from 28.91 ± 6.44 IU/L in patients with a MUST score of 1 to 35.07 ± 10.19 IU/L in those with a score of 5 (F = 2.487; p = 0.024; R = 0.154; R2 = 0.024; η = 0.263; η2 = 0.069). The gene discussed is ADA; the disease is nutritional deficiency disease.