Mild anaemia was prevalent among more than half of P. falciparum-infected schoolchildren and significantly associated with falciparum malaria (AOR = 5.8, 95.0% CI 2.39–14.17; p < 0.001), with a mean Hb concentration of 10.7 ± 1.0 g/dL. The gene discussed is GSTM1; the disease is Plasmodium falciparum malaria.