“…Our re sults are in agreement with those reported by Bienzle et al [ 1 ] in Nigeria and Steinberg et al [7] in a large US study. In contrast, the higher frequency of G-6-PD deficiency among SS pa tients was described in Jamaica [2], New York [6], Ghana [3] and Saudi Arabia [8], These dis crepancies may be the result of several factors, including the study of a small number of pa- tients, the use of methods for detection of G-6-PD that are unreliable in patients with sickle cell disease and the study of populations with different genetic backgrounds [7], The racial background of the Brazilian population with sickle cell disease is different from those of the American, Jamaican and African pop ulations, where the largest investigations were performed. Although the HbS gene is of Afri can origin, there is a more significant admix ture with Europeans, as indicated by a large proportion of patients classified as 'light mullatoes' [23], In this population, the frequencies of G-6-PD A -and G-6-PD A among SS pa tients were both slightly lower than those re ported in Nigeria [1], Jamaica [2] and some US populations [7,12].…”