Evaluation of blood cell count using an automatic hematology analyzer to optimize collection of peripheral blood progenitor cells by leukapheresis.

BACKGROUND: Autologous stem cell transplantation is a treatment modality for several diseases. Prediction of successful mobilization may be useful to optimize hematopoietic stem cell collection. STUDY DESIGN AND METHODS: This was a retrospective study with data from transplantation candidates between September 2015 and December 2021 being analyzed. The medical record of each patient was reviewed to mine mobilization information. The laboratory data analyzed were CD34+ cell enumeration and pre-collection peripheral blood cell count. The primary outcome, good mobilization, was defined as a CD34+ cell count ≥20/µL. RESULTS: This study included 807 patients. Increased patient weight, low mean corpuscular volume, high nucleated red blood cells, peripheral blood mononuclear cell and immature granulocyte counts were significantly associated with good mobilization. In addition, patients diagnosed with multiple myeloma were two times more likely to be good mobilizers than patients with lymphoma. The model was applied to a validation set to identify patients who underwent apheresis (CD34+ cell count ≥10 µL), resulting in a sensitivity of 69 %, a specificity of 95 %, positive predictive value of 98 %, and a negative predictive value of 50 %. CONCLUSION: Success in mobilization was greater in patients who underwent the first mobilization cycle and who had a diagnosis of multiple myeloma. Furthermore, higher body weight, and nucleated red blood cells, immature granulocytes and mononuclear cell counts, as well as low mean corpuscular volumes, were associated with successful mobilization.

Clinical, laboratory, and molecular characteristics of a cohort of children with hemoglobinopathy S/betathalassemia

ABSTRACT Introduction: Hemoglobinopathy Sβ-thalassemia (HbSβ-thal) has a wide range of clinical and laboratory severity. There is limited information on the natural history of HbSβ-thal and its modulating factors. We described the molecular, hematological, and clinical characteristics of a cohort of children with HbSβ-thal and estimated its incidence in Minas Gerais, Brazil. Methods: Laboratory and clinical data were retrieved from medical records. Molecular analysis was performed by HBB gene sequencing, PCR-RFLP, gap-PCR, and MLPA. Results: Eighty-nine children were included in the study. Fourteen alleles of β-thal mutations were identified. The incidence of HbSβ-thal in the state was 1 per 22,250 newborns. The most common βS-haplotypes were CAR and Benin. The most frequent βthal-haplotypes were V, II, and I. Coexistence of 3.7 kb HBA1/HBA2 deletion was present in 21.3 % of children. β-thalassemia mutations were associated with several clinical and laboratory features. In general, the incidence of clinical events per 100 patient-years was similar for children with HbSβ0-thal, IVS-I-5 G>A, and IVS-I-110 G>A. Children with HbSβ+-intermediate phenotypes had a more severe laboratory and clinical profile when compared with those with HbSβ+-mild ones. βS-haplotypes and α-thalassemia did not meaningfully influence the phenotype of children with HbSβ-thal. Conclusion: The early identification of b-thalassemia alleles may help the clinical management of these children. © 2023 Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular. Published by Elsevier España, S.L.U. This is an open access article under the CC BY-NC-ND license

Is Severity Score Associated With Indication for Hematopoietic Stem Cell Transplantation in Individuals With Sickle Cell Anemia?

Manifestations of sickle cell disease (SCD) begin early in childhood and cause morbidity and decreased life expectancy. Hematopoietic stem cell transplantation (HSCT) is curative but associated with risk of mortality attributable to the transplant. This risk should be counterbalanced with SCD morbidity and mortality. A severity score using a Bayesian network model was previously validated to predict the risk of death in adult individuals with SCD. The objective of this study is to calculate the severity scores of participants in a multicenter cohort of Brazilians with SCD, using a previously published Bayesian network-derived score, associated with risk of death and then compare the severity scores between participants with and without an indication for HSCT as defined by the Brazilian Ministry of Health (MoH) criteria. This is an observational, retrospective study. We analyzed 2063 individuals with sickle cell anemia from the Recipient Epidemiology and Donor Evaluation Study-III Brazil SCD cohort and applied a Bayesian network-derived score to compare candidates and non-candidates for HSCT according to the Brazilian MoH transplant criteria. Classical statistical methods were used to analyze data and make comparisons. We compared severity scores between cohort members with (n = 431) and without (n = 1632) HSCT indications according to Brazilian MoH. Scores were not different in adult participants with ≥1 HSCT indication when compared to those with no indication (mean 0.342 versus 0.292; median 0.194 versus 0.183, P = .354) and receiver operating characteristic curves did not demonstrate an obvious threshold to differentiate participants with or without HSCT indications. Severity score may predict risk of death but does not differentiate HSCT candidates. Current indications should be evaluated to ensure that patients with more severe disease who might benefit from HSCT are appropriately identified.

Association between inflammatory molecules, nitric oxide metabolites and leg ulcers in individuals with sickle cell anemia

Abstract Introduction Leg ulcers (LUs) are relatively common in patients with sickle cell anemia (SCA). The role of inflammation and nitric oxide (NO) pathways in the pathophysiology of the LU is not understood. Objective The aim of this study was to verify the association between inflammatory molecules and nitric oxide metabolites (NOx) and the occurrence of the LU in patients with SCA. Method It was a cross-sectional study on adult participants with SCA followed at Fundação Hemominas, a public blood center in Brazil. Eligible participants were recruited and included in one of two groups: Group 1, comprised of cases with SCA (Hb SS) and at least one LU at the time of inclusion in the study and Group 2, comprised of controls with SCA without a history of LU, matched by sex and age to cases. Participants were interviewed to obtain sociodemographic data and blood samples were collected. Clinical and laboratory data were abstracted from medical records. Nitric oxide metabolites (NOx) and inflammatory molecules were quantified using an immunoassay and Multiplex xMAP® technology, respectively. Eighty-seven individuals were included, ranging in age from 17 to 61 years (mean 40 ± 10.7 years); 30 had LU and 57 were controls without LU. Results Participants with LU had significantly higher levels of interleukin 8 (IL-8), IL-10, IL-15, NOx and platelet and white blood cell (WBC) counts, when compared to those without LU. Participants with LU had a significantly higher risk of having a history of osteomyelitis and a higher use of antiseptic soap in bathing, when compared to those without LU. Conclusion In conclusion, our results showed that NOx, inflammatory molecules and hematological features were associated with LU in Brazilian adults with SCA.

Evaluation of insertion/deletion (I/D) polymorphisms of ACE gene and circulating levels of angiotensin II in congenital anomalies of the kidney and urinary tract.

BACKGROUND: Congenital Anomalies of the Kidney and the Urinary Tract (CAKUT) are defined as a heterogeneous group of anomalies that resulted from defects in kidney and urinary tract embryogenesis. CAKUT have a complex etiology. Genetic, epigenetic and environmental factors have been investigated in this context. Angiotensin II is a potent vasoconstrictor and exerts an important role in kidney embryogenesis. The angiotensin-converting enzyme (ACE) converts Angiotensin I into Angiotensin II (Ang II) and ACE gene has insertion/deletion (I/D) polymorphisms that have been evaluated in several nephropathies. This study aimed to evaluate whether the I/D polymorphisms of ACE gene and the circulating levels of Ang II are associated with any CAKUT phenotype or CAKUT in general. METHODS AND RESULTS: Our study was performed with 225 pediatric patients diagnosed with CAKUT and 210 age-and-sex matched healthy controls. ACE I/D alleles were analysed by real-time polymerase chain reaction (RT-PCR). The distribution of ACE I/D polymorphisms were compared between CAKUT patients and healthy controls, as well between ureteropelvic junction obstruction (UPJO), vesicoureteral reflux (VUR), multicystic dysplastic kidney (MCDK) phenotypes and control group. No statistical association was detected between ACE I/D polymorphism and CAKUT and UPJO, VUR, and MCDK phenotypes. In a subset of 80 CAKUT patients and 80 controls, plasma levels of Ang II were measured. No significant differences were found between CAKUT patients and controls, even in regard to comparisons of UPJO, VUR and MCDK with control group. CONCLUSION: Although CAKUT is a complex disease and the ACE gene may exert a role in kidney embryogenesis, CAKUT was not associated with any ACE I/D polymorphisms nor with differences in plasma levels of Ang II in this Brazilian pediatric population.

Influence of laboratory procedures on postthawing cell viability and hematopoietic engraftment after autologous peripheral blood stem cell transplantation.

BACKGROUND: The kinetics of hematopoietic recovery after autologous stem cell transplantation (ASCT) may be affected by laboratory procedures. The aim of this study was to evaluate the influence of characteristics of the cryopreserved units of peripheral blood stem cells (PBSC) on postthawing cell viability and engraftment outcomes after ASCT. STUDY DESIGN AND METHODS: This was a retrospective cohort study including individuals referred for ASCT. Cryopreservation was conducted at a single processing facility between 2014 and 2019, and patients received clinical care at six transplant centers. Covariates and outcome data were retrieved from participants' records. RESULTS: The study population comprised 619 patients (345 [55.7%] male). Median age was 53 years. Multiple myeloma was the most common diagnosis (62.7%). Higher preapheresis CD34+ cell count, lower nucleated cell (NC) concentration per cryobag, and composition of the cryoprotectant solution (5% dimethyl sulfoxide [DMSO] and 6% hydroxyethyl starch) were statistically significantly associated with higher postthawing cell viability. The linear regression model for time to neutrophil and platelet engraftment included the infused CD34+ cell dose and the composition of the cryoprotectant solution. Patients who had PBSC cryopreserved using 10% DMSO solution presented six times higher odds (odds ratio [OR] = 6.9; 95% confidence interval [CI]: 2.2-21.1; p = .001) of delayed neutrophil engraftment (>14 days) and two times higher odds (OR = 2.3, 95%CI: 1.4-3.7; p = .001) of prolonged hospitalization (>18 days). DISCUSSION: The study showed that mobilization efficacy, NC concentration, and the composition of the cryoprotectant solution significantly affected postthawing cell viability. In addition, the composition of the cryoprotectant solution significantly impacted engraftment outcomes and time of hospitalization after ASCT.

Functional polymorphisms of BCL11A and HBS1L-MYB genes affect both fetal hemoglobin level and clinical outcomes in a cohort of children with sickle cell anemia.

Fetal hemoglobin (HbF) ameliorates clinical severity of sickle cell anemia (SCA). The major loci regulating HbF levels are HBB cluster, BCL11A, and HMIP-2 (HBS1L-MYB). However, the impact of noncoding single-nucleotide polymorphisms (SNPs) in these loci on clinical outcomes and their functional role on regulating HbF levels should be better elucidated. Therefore, we performed comprehensive association analyses of 14 noncoding SNPs in five loci with HbF levels and with clinical outcomes in a cohort of 250 children with SCA from Southeastern Brazil, and further performed functional annotation of these SNPs. We found SNPs independently associated with HbF levels: rs4671393 in BCL11A (ß-coefficient = 0.28), rs9399137 in HMIP-2A (ß-coefficient = 0.16), and rs4895441 in HMIP-2B (ß-coefficient = 0.15). Patients carrying minor (HbF-boosting) alleles for rs1427407, rs93979137, rs4895441, rs9402686, and rs9494145 showed reduced count of reticulocytes (p < 0.01), while those carrying the T allele of rs9494145 showed lower white blood cell count (p = 0.002). Carriers of the minor allele for rs9402686 showed higher peripheral saturation of oxygen (p = 0.002). Patients carrying minor alleles in BCL11A showed lower risk of transfusion incidence rate ratio (IRR ≥ 1.3; p < 0.0001). This effect was independent of HbF effect (p = 0.005). Carriers of minor alleles for rs9399137 and rs9402686 showed lower risk of acute chest syndrome (IRR > 1.3; p ≤ 0.01). Carriers of the reference allele for rs4671393 showed lower risk of infections (IRR = 1.16; p = 0.01). In conclusion, patients carrying HbF-boosting alleles of BCL11A and HMIP-2 were associated with milder clinical phenotypes. Higher HbF concentration may underlie this effect.

Evidence for interactions between inflammatory markers and renin-angiotensin system molecules in the occurrence of albuminuria in children with sickle cell anemia.

Sickle cell anemia (SCA) is an important cause of chronic kidney disease, but its pathophysiology is not completely understood. The aim of this study was to compare inflammatory biomarkers in urine samples of SCA children with and without albuminuria, and to explore correlations with renin-angiotensin system (RAS) molecules. A cross-sectional study of 213 children selected from the Minas Gerais state cohort were assigned to two groups: Group 1-89 children with SCA who had albuminuria; Group 2-124 children with SCA and normal albuminuria matched by age and sex with group 1. A subset of 89 children was prospectively followed for a median time of 1.1 year. Inflammatory biomarkers (chemokines and cytokines) in urine were measured using cytometric beads array, and RAS molecules were measured by ELISA. Children with albuminuria had significantly higher urinary levels of IP-10/CXCL10, MCP-1/CCL2, MIG/CXCL9, IL-8/CXCL8, IL-12p70, TNF, IL-10, and IL-6 than patients with normal albuminuria. In the correlation analysis, albumin/creatinine ratio was significantly and positively correlated with IP-10/CXCL10, MCP-1/CCL2, MIG/CXCL9, IL-8/CXCL8, TNF, IL-10, and IL-6. Significant correlations were found between inflammatory and RAS molecules. In the prospective analysis, cumulative risk of persistent albuminuria was higher for children with urinary levels of IP-10/CXCL10 or IL-6 above the 50th percentile. Our data showed that inflammatory markers and RAS molecules might contribute to the occurrence of albuminuria in children with SCA, suggesting that both pathways interact in sickle cell nephropathy.

Genetic, laboratory and clinical risk factors in the development of overt ischemic stroke in children with sickle cell disease

ABSTRACT Cerebrovascular disease, particularly stroke, is one of the most severe clinical complications associated with sickle cell disease and is a significant cause of morbidity in both children and adults. Over the past two decades, considerable advances have been made in the understanding of its natural history and enabled early identification and treatment of children at the highest risk. Transcranial Doppler screening and regular blood transfusions have markedly reduced the risk of stroke in children. However, transcranial Doppler has a limited positive predictive value and the pathophysiology of cerebrovascular disease is not completely understood. In this review, we will focus on the current state of knowledge about risk factors associated with ischemic stroke in patients with sickle cell disease. A search of PubMed was performed to identify studies. Full texts of the included articles were reviewed and data were summarized in a table. The coinheritance of alpha-thalassemia plays a protective role against ischemic stroke. The influence of other genetic risk factors is controversial, still preliminary, and requires confirmatory studies. Recent advances have established the reticulocyte count as the most important laboratory risk factor. Clinical features associated with acute hypoxemia as well as silent infarcts seem to influence the development of strokes in children. However, transcranial Doppler remains the only available clinical prognostic tool to have been validated. If our understanding of the many risk factors associated with stroke advances further, it may be possible to develop useful tools to detect patients at the highest risk early, improving the selection of children requiring intensification therapy.

Interleukin-10 haplotypes are not associated with acute cerebral ischemia or high-risk transcranial Doppler in a newborn cohort of 395 children with sickle cell anemia

ABSTRACT Background: The etiology of stroke, a severe complication of sickle cell anemia, involves inflammatory processes. However, the pathogenetic mechanisms are unknown. The aim of this study was to evaluate the influence of interleukin-10 polymorphisms and haplotypes on the risk of acute cerebral ischemia and high-risk transcranial Doppler in 395 children with sickle cell anemia from the state of Minas Gerais, Brazil. Methods: Interleukin-10 haplotypes were determined by polymerase chain reaction-restriction fragment length polymorphism and sequencing. The outcomes studied were acute cerebral ischemia and high-risk transcranial Doppler. Clinical data were retrieved from the children's records. Results: There was no statistically significant difference in the frequencies of polymorphisms and haplotypes between children with and without acute cerebral ischemia or children with or without high-risk transcranial Doppler. These data are consistent with a previous report that showed an absence of association between interleukin-10 plasma levels and high-risk transcranial Doppler velocity in children with sickle cell anemia. Conclusion: Interleukin-10 haplotypes were not associated with the risk of acute cerebral ischemia or high-risk transcranial Doppler velocity in children with sickle cell anemia from the state of Minas Gerais, Brazil.

Reticulocyte count is the most important predictor of acute cerebral ischemia and high-risk transcranial Doppler in a newborn cohort of 395 children with sickle cell anemia.

Stroke is a severe clinical manifestation of sickle cell anemia (SCA). Despite the prognostic relevance of transcranial Doppler (TCD), more accurate tools to assess stroke risk in children with SCA are required. Here, we describe the effect of clinical, laboratory, and molecular features on the risk of stroke and high-risk TCD in children from the newborn cohort of Minas Gerais, Brazil. Outcomes studied were acute cerebral ischemia and high-risk TCD. Clinical and hematological data were retrieved from children's records. Genetic markers, which were known for their association with stroke risk, were genotyped by polymerase chain reaction/restriction fragment length polymorphism and sequencing. The cumulative incidence of acute cerebral ischemia by the age of 8 years was 7.4 % and that of high-risk TCD by the age of 11.5 years was 14.2 %. The final multivariate model for acute cerebral ischemia risk included high white blood cell count and reticulocyte count, acute chest syndrome rate, and the single nucleotide polymorphisms (SNPs) TEK rs489347 and TNF-α rs1800629. The model for high-risk TCD included high reticulocyte count and the SNPs TEK rs489347 and TGFBR3 rs284875. Children with risk factors should be considered for intensive risk monitoring and for intervention therapy.

Glucose-6-Phosphate Dehydrogenase Deficiency in Brazilian Children With Sickle Cell Anemia is not Associated With Clinical Ischemic Stroke or High-Risk Transcranial Doppler.

BACKGROUND: Stroke is a severe complication of sickle cell anemia (SCA). The role of glucose-6-phosphate dehydrogenase (G6PD) deficiency in the development of stroke in children with SCA is controversial. PROCEDURE: The aim of this study was to investigate the association of clinical ischemic stroke, high-risk transcranial Doppler measurements (TCD), and hematological features with molecular variants usually linked to G6PD deficiency or with the biochemical activity of G6PD in a cohort of 395 Brazilian children with SCA. G6PD activity was quantitatively determined using an enzymatic-colorimetric assay. G6PD mutations were determined by PCR-RFLP and sequencing. Clinical and hematological data were retrieved from the children's records. RESULTS: The prevalence of molecularly defined deficiency (hereafter, molecular deficiency) was 4.3% (95% confidence interval: 2.3-6.3%). The mean G6PD activity was 16.88 U/g hemoglobin (Hb) (standard error of the mean [SEM] 0.28) in the group without G6PD molecular deficiency and 8.43 (SEM 1.01) U/g Hb in the group with G6PD A(-) molecular deficiency. G6PD molecular deficiency was not associated with any hematological features. No effects of G6PD molecular deficiency on clinical ischemic stroke or high-risk TCD were detected. The mean G6PD activity was similar in children who had clinical ischemic stroke and in those without stroke. Similar results were obtained in analyses comparing children who had high-risk TCD and those without high-risk TCD. CONCLUSIONS: Our study demonstrated that G6PD molecular deficiency was not associated either with clinical ischemic stroke or high-risk TCD. Similarly, we found no associations between G6PD enzyme activity and stroke or high-risk TCD. Small sample size precludes definitive conclusions.

Clinical, hematological and genetic data of a cohort of children with hemoglobin SD

Introduction The hemoglobin FSD is very uncommon in newborn screening programs for sickle cell disease. In the program of Minas Gerais, Brazil, the clinical course of children with hemoglobin SD was observed to be heterogeneous. The objective of this study was to estimate the incidence (1999­2012) and to describe the natural history of a cohort of newborns with hemoglobin SD. Methods Isoelectric focusing was the primary method used in newborn screening. Polymerase chain reaction-restriction fragment length polymorphism and gene sequencing were used to identify mutant alleles and for haplotyping. Gap-polymerase chain reaction was used to detect alpha-thalassemia. Results Eleven cases of hemoglobin S/D-Punjab and eight of Hb S-Korle Bu were detected. Other variants with hemoglobin D mobility were not identified. All hemoglobin D-Punjab and hemoglobin Korle Bu alleles were associated with haplotype I. Among the children with hemoglobin S/D-Punjab, there were four with the ßS CAR haplotype, six with the Benin haplotype, and one atypical. Results of laboratory tests for hemoglobin S/D-Punjab and hemoglobin S-Korle Bu were: hemoglobin 8.0 and 12.3 g/dL (p-value <0.001), leukocyte count 13.9 × 109/L and 10.5 × 109/L (p-value = 0.003), reticulocytes 7.5% and 1.0% (p-value <0.001), hemoglobin F concentration 16.1% and 6.9% (p-value = 0.001) and oxygen saturation 91.9% and 97% (p-value = 0.002), respectively. Only hemoglobin S/D-Punjab children had acute pain crises and needed blood transfusions or hydroxyurea. Those with the Benin ßS haplotype had higher total hemoglobin and hemoglobin F concentrations compared to the CAR haplotype. Transcranial Doppler was normal in all children. Conclusion The clinical course and blood cell counts of children with hemoglobin S/D-Punjab were very similar to those of hemoglobin SS children. In contrast, children with hemoglobin S-Korle Bu had clinical course and blood cell counts like children with the sickle cell trait.

Association of alpha-thalassemia, TNF-alpha (-308G>A) and VCAM-1 (c.1238G>C) gene polymorphisms with cerebrovascular disease in a newborn cohort of 411 children with sickle cell anemia.

Cerebrovascular disease (CVD) is a severe complication associated with sickle cell anemia. Abnormal transcranial Doppler (TCD) identifies some children at high risk, but other markers would be helpful. This cohort study was aimed at evaluating the effects of genetic biomarkers on the risk of developing CVD in children from Minas Gerais, Brazil. Clinical and hematological data were retrieved from children's records. Outcomes studied were overt ischemic stroke and CVD (overt ischemic stroke, transient ischemic attack, abnormal TCD, or abnormal cerebral angiography). Out of 411 children, 386 (93.9%) had SS genotype, 23 (5.6%) had Sß(0)-thal and two had severe Sß(+)-thal (0.5%). Frequency of CVD was lower in Sß-thal group (p=0.05). No effect of VCAM-1 polymorphism on stroke or CVD risks was detected. Cumulative incidence of stroke was significantly higher for children with TNF-α A allele (p=0.02) and lower for children with HBA deletion (p=0.02). However, no association between CVD and TNF-α -308G>A was found. CVD cumulative incidence was significantly lower for children with HBA deletion (p=0.004). This study found no association between VCAM1 c.1238G>C and stroke. An association between stroke and TNF-α -308A allele has been suggested. Our results have confirmed the protective role of HBA deletion against stroke and CVD.

De novo alpha 2 hemoglobin gene (HBA2) mutation in a child with hemoglobin M Iwate and symptomatic methemoglobinemia since birth

Cyanosis in an apparently healthy newborn baby may be caused by hemoglobin variants associated with the formation of methemoglobin, collectively known as M hemoglobins. They should not be confused with genetic alterations in methemoglobin reductase enzyme systems of red cells since treatment and prognosis are completely different. A newborn male child was noted to be significantly cyanotic at birth and is the basis for this report. Hemoglobin isoelectric focusing, acid and alkaline gel electrophoresis, and HBA/HBB gene sequencing were performed for the child, both parents and a sister. The newborn child was treated with methylene blue in an intensive care unit fearing that he had a defective reductase system and exposure to oxidant drugs or toxins. Newborn hemoglobin screening with high performance liquid chromatography was abnormal on the 10th and 45th days but no conclusive diagnosis was reached. Cyanosis persisted up to four years of age with no other symptoms. Hemoglobin M Iwate [alpha2 87(F8) His>Tyr, HBA2:c.262C>T] was detected. It was not present in the child's presumed mother, father, sister, and brother. The analysis of 15 short tandem repeats in the trio demonstrated a de novo mutation occurrence (p-value < 1 × 10 -8). The family was reassured that no further action was necessary and genetic counseling was provided. Methemoglobins should be considered for differential diagnosis of cyanosis in newborns even if no familial cases are detected. Except for cosmetic consequences, the clinical course of patients with hemoglobin M Iwate is unremarkable.

Efeitos da Talassemia Alfa nas manifestações clínicas e hematológicas da Anemia Falciforme: uma revisão sistemática / Effects of alpha-thalassemia on the clinical and hematologic manifestations of sickle cell anemia: a systematic review

A anemia falciforme, doença hereditária causada por uma mutação no gene da globina beta, produz uma diversidade de expressões fenotípicas nos indivíduos acometidos. O quadro clínico é bastante heterogêneo e varia muito entre indivíduos. O nível de Hb F, o genótipo de talassemia alfa, o haplótipo do agrupamento de genes da globina beta, a idade, o gênero e fatores ambientais são modificadores importantes do quadro clínico da doença. Esta revisão concentra-se nos efeitos da talassemia alfa nas manifestações clínicas e laboratoriais da anemia falciforme. A coexistência da talassemia alfa modifica características laboratoriais da anemia falciforme, bem como a freqüência de manifestações clínicas e, até mesmo, a sobrevida dos indivíduos. Entretanto, sua simples presença ou ausência não permite prever, isoladamente, o quadro clínico dos pacientes. Daí surge a necessidade de estudar outros fatores moduladores que possam ser utilizados em conjunto para definir subfenótipos da doença e, assim, serem utilizados como ferramenta clínica no acompanhamento dos pacientes.

Sickle cell anemia, a hereditary disease caused by a single mutation in the beta globin gene produces a diversity of phenotypic expression in affected individuals. The clinical features are heterogeneous and are remarkably variable in different patients. Hb F concentration, alpha-thalassemia genotype, beta-globin gene cluster haplotype, age, gender and environmental factors are important modifiers of the disease. This review focuses on the effect of alpha-thalassemia genotype on the clinical and laboratorial manifestations of sickle cell anemia. Coexistence of alpha-thalassemia modifies laboratory features of sickle cell anemia, as well as the frequency of clinical manifestations and even the survival of patients. However, the coinheritance of alpha-thalassemia does not predict, alone, the clinical profile of patients with sickle cell anemia. Hence the need to study other modulating factors that may be used together in order to define subphenotypes of the disease and to use them as clinical tools in patients? follow-up.