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

Sickle cell disease and acute leukemia: one case report and an extensive review

Population-based studies and case reports suggest that there may be an increased risk of acute leukemia associated with sickle cell disease (SCD). Following the description of a new case report, an extensive review of the literature identified 51 previously described cases. Most cases study showed myelodysplastic features confirmed, when available, by genetic markers such as chromosome 5 and/or chromosome 7 abnormalities and TP53 gene mutations. The increased risk of leukemogenesis is certainly multifactorial and related to the pathophysiologic mechanisms of the clinical manifestations of SCD. Chronic hemolysis and secondary hemochromatosis may cause increased chronic inflammation, resulting in persistent marrow stress, which could potentially compromise the genomic stability of the hematopoietic stem cells generating genomic damage and somatic mutations over the course of SCD and its treatment, resulting in a clone that led to acute myeloid leukemia.

Transcranial Doppler sonography and the effect of haematopoietic stem cell transplantation in sickle cell disease

Background

Sickle cell disease (SCD) is one of the most prevalent monogenetic diseases worldwide and one of the most serious complications is stroke. Transcranial Doppler (TCD) demonstrated to be highly predictive for an imminent stroke by measuring blood flow velocities in the basal cerebral arteries. Currently, the only curative therapy for SCD is hematopoietic stem cell transplantation (HSCT). The aim of this study is to verify the correlation between blood flow velocities and stroke including the effect of HSCT.

Methods

In our retrospective single-center study a total of 26 sickle cell patients (HbSS, HbSß⁺-thalassemia, HbSSα-thalassemia minima, HbSSα-thalassemia minor and HbSC) were analyzed between 2010 and 2016. The highest time averaged maximum mean blood flow velocity (TAMMV) measured was documented and evaluated with respect to SCD genotype and effect of HSCT. Acute and symptomatic as well as silent strokes were recorded as separate parameters.

Results

In our study, ten patients had normal blood flow velocities before HSCT (six HbSS and four HbSß⁺-thalassemia patients) and 13 patients presented with abnormal TCD (eight HbSS, three HbSSα-thalassemia minima, one HbSSα-thalassemia minor and one HbSC). Thirteen of 26 study participants (ten HbSS and three HbSß⁺-thalassemia patients) received HSCT. In two patients, TAMMV in basal cerebral arteries remained “normal”, in one they remained conditional and in one TAMMV was reduced to normal. Four of 26 study participants (15.4%), including all patients with HbSS genotype, presented with a stroke, but none had “abnormal” TAMMV with TCD performed after the onset of stroke in each case. At the time we performed the TCD, the patients had already suffered the stroke.

Conclusion

In our study, none of the patients with stroke displayed abnormal blood flow velocities in TCD. Yet, HSCT at this stage of the disease still had a positive effect on TAMMV. Further studies are needed whether this effect converts into reduced stroke risk at all or only selected SCD patients undergoing HSCT.

Is chronic use of hydroxyurea safe for patients with sickle cell anemia? An account of genotoxicity and mutagenicity

Sickle cell anemia (SCA) is a hereditary hematological disease that is characterized by a point mutation in the beta globin S gene and has no specific treatment; hydroxyurea (HU) is the only therapeutic agent used in clinical practice. In the present study, we evaluated the deoxyribonucleic acid (DNA) damage index (DI) and chromosomal damage in leukocytes of adult patients with SCA with and without HU. The DI was assessed by the comet assay and chromosomal damage by the leukocyte micronucleus test of adult patients treated with HU (SCA-HU) and without the use of HU (SCA-NoHU). This is a cross-sectional study with 77 patients with SCA who attended a referral hospital in Fortaleza, Brazil. The control group (CG) consisted of 58 reportedly healthy individuals. The comparisons of means were performed by analysis of variance and Tukey's post-test. Values of P < 0.05 were considered statistically significant. SCA-NoHU patients had statistically higher DI values and a statistically significantly higher frequency of micronuclei compared to the CG. In addition, HU treatment accentuated DNA lesions by significantly increasing both parameters in treated patients (SCA-HU). HU potentiates DNA damage and the occurrence of chromosomal damage, which may promote genomic instability, mutation occurrence, and carcinogenesis. Studies are needed to evaluate the involved pathways, repair mechanisms, and the clinical impact that such damage can cause. Environ. Mol. Mutagen. 60:302-304, 2019. © 2018 Wiley Periodicals, Inc.

Inheritance of the Bantu/Benin haplotype causes less severe hemolytic and oxidative stress in sickle cell anemia patients treated with hydroxycarbamide

Beta S-globin gene cluster haplotypes (β(S)-haplotypes) can modulate the response to hydroxycarbamide (HC) treatment in sickle cell anemia (SCA) patients. In Brazil, the most common haplotypes are Bantu and Benin, and both confer a poor prognosis for patients when untreated with HC. We evaluated oxidative and hemolytic biomarkers in 48 SCA patients undergoing HC treatment separated in three subgroups: Bantu/Bantu, Bantu/Benin and Benin/Benin haplotype. On the basis of reduced haptoglobin (HP) levels, patients with Bantu/Bantu haplotypes had 3.0% higher hemolysis degree when compared with those with Bantu/Benin haplotypes (P=0.01). The Benin/Benin patients had 53.6% greater lipid peroxidation index than the Bantu/Bantu patients (P=0.01) because of evaluated thiobarbituric acid reactive species levels. The Bantu/Benin subgroup had intermediate levels of hemolytic and oxidative stress markers compared with the homozygous subgroups. Through strict inclusion criteria adopted, as well as consolidated and well-described hemolytic and the oxidative parameters evaluated, we suggest a haplotype-interaction response to HC treatment mediated by a 'balance' between the genetic factors of each haplotype studied.

The effect of hydroxyurea on compound heterozygotes for sickle cell-hemoglobin D-Punjab--a single centre experience in eastern India

BACKGROUND

Although hydroxyurea is the only effective agent for the treatment of sickle cell disease, published experience with this drug is limited to treatment of homozygous sickle cell anemia and HbS/β thalassemia. The role of hydroxyurea in the treatment of patients with HbSD-Punjab, a rare hemoglobinopathy with phenotypic expression similar to that of sickle cell anemia is unknown.

PROCEDURE

Over a period of 10 years, we followed 42 patients with HbSD-Punjab, of which 20 presented with severe clinical manifestations (≥3 episodes of VOC and/or ≥2 units of blood transfusion in the previous 12 months). These 20 patients were enrolled for treatment with hydroxyurea at a dose of 10 mg/kg/day and followed prospectively for a period of 24 months.

RESULTS

The frequency of VOC decreased significantly and none of them required blood transfusion while receiving hydroxyurea. The HbF, total hemoglobin, MCV, MCH, and MCHC levels increased significantly, whereas HbS, WBC, platelet count, total serum bilirubin, and LDH levels decreased significantly in all the patients. No short-term drug toxicity was observed.

CONCLUSION

This study describes the use of hydroxyurea therapy in patients with HbSD-Punjab. Low dose hydroxyurea (10 mg/kg/day) was found to be effective in reducing the clinical severity in patients with HbSD-Punjab without any short-term toxicity. In view of easy affordability amongst poor patients, widespread acceptability by patients and doctors, the need of infrequent monitoring and its potential effectiveness, low dose hydroxyurea is suitable for treatment of patients with HbSD-Punjab.

Cytotoxicity and DNA damage in the neutrophils of patients with sickle cell anaemia treated with hydroxyurea

Hydroxyurea (HU) is the most important advance in the treatment of sickle cell anaemia (SCA) for preventing complications and improving quality of life for patients. However, some aspects of treatment with HU remain unclear, including their effect on and potential toxicity to other blood cells such as neutrophils. This study used the measurement of Lactate Dehydrogenase (LDH) and Methyl ThiazolTetrazolium (MTT) and the comet assay to investigate the cytotoxicity and damage index (DI) of the DNA in the neutrophils of patients with SCA using HU.In the LDH and MTT assays, a cytoprotective effect was observed in the group of patients treated, as well as an absence of toxicity. When compared to patients without the treatment, the SS group (n=20, 13 women and 07 men, aged 18-69 years), and the group of healthy individuals (AA) used as a control group (n=52, 28 women and 24 men, aged 19-60 years), The SSHU group (n=21, 11 women and 10 men, aged 19-63 years) showed a significant reduction (p<0.001) in LDH activity and an increase in the percentage of viable cells by the MTT (p<0.001). However, the SSHU group presented significantly higher DI values (49.57±6.0 U/A) when compared to the AA group (7.43 ± 0,94U/A) and the SS group (22.73 ±5.58 U/A) (p<0.0001), especially when treated for longer periods (>20 months), demonstrating that despite the cytoprotective effects in terms of cell viability, the use of HU can induce DNA damage in neutrophils.