DNA damage in leukocytes of sickle cell anemia patients is associated with hydroxyurea therapy and with HBB*S haplotype

Abstract

Hydroxyurea (HU) is the primary pharmacologic agent for preventing the complications and improving the quality of life of sickle cell anemia (SCA) patients. Although HU has been associated with an increased risk of leukemia in some patients with myeloproliferative disorders, the mutagenic and carcinogenic potential of HU has not been established. This study used the alkaline comet assay to investigate DNA damage in peripheral blood leukocytes from 41 individuals with SCA treated with HU (SCAHU) and from 26 normal individuals. The presence of HbS and the analysis of the haplotypes of the beta S gene cluster were done by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). The damage index (DI) in the SCAHU group was significantly higher than in controls (p<0.001). Neither gender nor age was associated with DNA damage in controls or SCAHU individuals. Among the SCAHU individuals, DI was significantly influenced by length of HU treatment (p=0.0039) and BMI (p=0.001). Individuals with length of HU treatment≥20 months and BMI≤20kg/m2 had a significantly greater DI than those with length of HU treatment<20 months and BMI>20kg/m2. No significant influence of mean HU dose was observed on DI (p=0.950). However, individuals who received a mean HU dose≥20mg/kg showed a higher DI than those who received less. Furthermore, an association was observed between DI damage and HBB*S gene haplotypes. DI values for the Bantu/Bantu haplotype was greater when compared to the Benin/Benin haplotype; and the Bantu/Benin haplotype had a DI lower than the Bantu/Bantu haplotype and greater than the Benin/Benin haplotype. Our results show that DNA damage in sickle cell anemia is associated not only with treatment with HU but also with genotype.