Cotrimoxazole may directly impact erythropoiesis, causing a reduction in red cell number, yet simultaneously lead to increased Hb levels because of its beneficial effects at reducing malaria and other infections.29–31 Even still, our study results suggest a cause for concern, as HIV-associated anemia has also been shown to increase the risk of mortality.13 The gene discussed is GSTM1; the disease is anemia (phenotype).