Genotypic influence of α-deletions on the phenotype of Indian sickle cell anemia patients.

Background: Some reports have shown that co-inheritance of α-thalassemia and sickle cell disease improves hematological parameters and results in a relatively mild clinical picture for patients; however, the exact molecular basis and clinical significance of the interaction between α-thalassemia and sickle cell disease in India has not yet been described. There is little agreement on the clinical effects of α-thalassemia on the phenotype of sickle cell disease.

Methods: Complete blood count and red cell indices were measured by an automated cell analyzer. Quantitative assessment of hemoglobin variants HbF, HbA, HbA(2), and HbS was performed by high performance liquid chromatography (HPLC). DNA extraction was performed using the phenol-chloroform method, and molecular study for common α-deletions was done by gap-PCR.

Results: Out of 60 sickle cell anemia patients, the α-thalassemia genotype was found in 18 patients. Three patients had the triplicated α-genotype (Anti α-3.7 kb), and the remaining patients did not have α-deletions. This study indicates that patients with co-existing α-thalassemia and sickle cell disease had a mild phenotype, significantly improved hematological parameters, and fewer blood transfusions than the patients with sickle cell anemia without co-existing α-deletions.

Conclusion: Co-existence of α-thalassemia and sickle cell anemia has significant effects on the phenotype of Indian sickle cell patients.