Association of G6PD^202A,376G with lower haemoglobin concentration but not increased haemolysis in patients with sickle cell anaemia

The genetic bases of the highly variable degrees of anaemia and haemolysis in persons with Hb SS are not fully known, but several studies have indicated that G6PD deficiency is not a factor. The G6PD^202A and G6PD ^376G alleles and α-thalassaemia were determined by molecular genetic testing in 261 children and adolescents with Hb SS in a multicentre study. G6PD^202A,376G (G6PD A-) was defined as hemizygosity for both alleles in males and homozygosity in females. Among the participants 41% were receiving hydroxycarbamide. The prevalence of G6PD^202A,376G was 13·6% in males and 3·3% in females with an overall prevalence of 8·7%. G6PD^202A,376G was associated with a 10 g/l decrease in haemoglobin concentration (P = 0·008) but not with increased haemolysis as measured by lactate dehydrogenase, bilirubin, aspartate-aminotransferase, reticulocyte count or a haemolytic component derived from these markers (P > 0·09). Similar results were found within a sub-group of children who were not receiving hydroxycarbamide. By comparison, single and double α-globin deletions were associated with progressively higher haemoglobin concentrations (P = 0·005 for trend), progressively lower values for haemolytic component (P = 0·007), and increased severe pain episodes (P < 0·001). In conclusion, G6PD^202A,376G may be associated with lower haemoglobin concentration in sickle cell anaemia by a mechanism other than increased haemolysis.