Almost half of the patients with iron deficiency received iron supplementation during hospital stay in whom severity of iron deficiency was higher compared to the patients not receiving supplements (mean Hb 10.4 ± 1.6 g/dl vs. 11.1 ± 1.7 g/dl, p = 0.044; mean TSAT 10.5 ± 3.4% vs. 11.5 ± 3.0%, p = 0.599, respectively). The gene discussed is GSTM1; the disease is nutritional disorder.