Distribution of the different β haplotypes in the SCA cohort as a function of α thalassemia and G6PD deficiency in the 3 major homozygous β haplotypes. (A) Number of patients with the different combinations of β haplotypes. The CAR haplotype was the most prevalent allele (43.2%), followed by BEN (34.6%), SEN (17.0%), CAM (2.7%), and atypical (2.5%). Homozygosity for β haplotype was present in 74% of SS patients; ie, CAR/CAR (37.4%), BEN/BEN (24.3%), SEN/SEN (12.1%), and CAM/CAM (0.2%). (B) Prevalence of α thalassemia in the 3 major homozygous β haplotypes. α thalassemia was present in 44.1% of the patients, with 32.8% being heterozygous for the α^−3.7 deletion (3 α genes) and 11.4% being homozygous (2 α genes), whereas 0.5% had 5 α genes (patient heterozygous for the anti-3.7 triplication). The prevalence of α thalassemia was significantly higher (P < .001) in CAR/CAR patients (55.3%) than in any other homozygous β haplotypes (BEN/BE, 29.8%; SEN/SEN, 27.1%). (C) Prevalence of G6PD deficiency in the 3 major homozygous β haplotypes. The overall prevalence of G6PD deficiency was 10.6% and was similar in patients with (10.9%) or without α thalassemia (10.4%). However its prevalence was significantly lower (P = .01) in SEN/SEN patients (1.6%) than in CAR/CAR (14.2%) and BEN/BEN (10.3%) patients. The prevalence of G6PD deficiency was significantly lower (P = .01) in SEN/SEN patients (1.6%) than in CAR/CAR (14.2%) and BEN/BEN (10.3%) patients.