GSTM1 and Schnyder corneal dystrophy: In Benin, according to research, it is estimated that >4.8 % of the population is affected by major sickle cell syndromes; the prevalence of sickle cell traits is 22.3 % for Hb S compared to 10.21 % for Hb C.9, 10, 11 Thus, the high prevalence among Beninese populations makes SCD a real public health problem.