The effect of the coinheritance of Glucose-6-phosphate dehydrogenase deficiency on the severity of sickle cell disease

Background: Sickle cell disease (SCD) and glucose-6-phosphate dehydrogenase (G6PD) deficiency are inherited disorders associated with chronic haemolysis. Therefore, coinheritance of both disorders could worsen haemolysis in the former and compound a haemolytic crisis. This study compared clinical and laboratory features of deficient and non-deficient SCD patients and the G6PD activities of SCD patients and apparently healthy controls. Materials and Methods: This is a case-control study of 175 SCD patients and 166 non-SCD controls. G6PD assay was carried out on haemolysate from washed red cells. The G6PD activity was measured by spectrophotometry. Results: The mean age of patients and controls was 27.3 +/- 9.4 and 35.9 +/- 9.7 years, respectively, with 75 (46.2%) and 87 (52.4%) being males, respectively. G6PD activity was similar in cases and controls (6.7 +/- 3.3 vs. 6.9 +/- 3.0 IU/gHb), respectively (P = 0.6). The prevalence of G6PD deficiency was higher in patients than controls (28.6% vs. 22.3%, P = 0.18), and SCD patients were twice more likely to have enzyme activities below 3.0 IU/gHb. No significant difference was observed in the clinical parameters between deficient and non-deficient patients. Deficient patients were more likely to have lower haematocrit (22.8 +/- 3.9% vs. 24.5 +/- 5%, P = 0.04) and non-significantly higher bilirubin and reticulocyte counts. Furthermore, in patients, severe deficiency resulted in higher bilirubin than in those with mild deficiency (60.5 vs. 21.7 IU/L, P < 0.001). G6PD activity correlated positively with haematocrit (r = 0.91, P = 0.01) and mean corpuscular haemoglobin concentration (r = 0.17, P = 0.02). Conclusions: Coinheritance of both disorders could worsen haemolysis in SCD patients, and care should, therefore, be taken in the choice of drugs in deficient SCD patients.