Therefore, in Latin American countries such as Colombia and Brazil where P. vivax is the main parasite causing malaria, it is recommended that PQ administration requires prior determination of G6PD status (normal or deficient), However, this recommendation is not followed in most endemic countries of the continent, and it is uncertain what proportion of malaria cases, mainly P. vivax that are treated with therapeutic protocols including PQ, develop haemolysis. The gene discussed is G6PD; the disease is malaria.