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The study estimated α-thalassemia (α-thal) prevalence and assessed its associations with clinical and hematological features in a random sample of Brazilian children with sickle cell anemia (208 Hb SS and 13 Hb S-β⁰-thal). α-Thalassemia genotyping was carried out by multiplex polymerase chain reaction (m-PCR) for seven alleles. Clinical and hematological data were retrieved from the 221 children's medical files. Their ages ranged from 2.5 to 10.4 years. Of the Hb SS children, 27.9% carried -α(3.7)/αα and 1.4% -α(3.7)/-α(3.7). The presence of α-thal was significantly associated with reduction in MCV, MCH, WBC values and reticulocyte counts. No significant association with blood transfusion or acute chest syndrome (ACS), was found. α-Thalassemia genotypes were strongly associated with reduction in risk for cerebrovascular disease (CVD) (conditional and abnormal transcranial Doppler or stroke; p = 0.007). The interaction of α-thal with other modulating factors should be investigated in order to define subphenotypes of the disease and to use them as clinical tools in the follow-up care of patients.

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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.

Background/Aims: β^S-Haplotype prevalence and its associations with clinical and hematological characteristics were assessed in Brazilian children with sickle cell anemia or Sβ⁰-thalassemia. Methods: A retrospective randomized cohort study was undertaken with 208 SS and 13 Sβ⁰-thalassemia children derived from the Newborn Screening Program of the state of Minas Gerais. β^S-Haplotypes were determined by PCR-RFLP. Results: Thirty-nine percent of the SS subjects had the CAR/CAR genotype, 33% had CAR/Ben, 24% had Ben/Ben, 1% had CAR/Atp, 1% had Ben/Atp, and 1% had Arab-Indian/Ben; 1% could not be characterized. Of the Sβ⁰-thalassemia children, 5 were CAR/undefined, 2 were Ben/undefined, and 1 was CAM/undefined. There was no significant association between β^S-haplotypes and the total Hb, Hb F, MCV, MCH, WBC, and reticulocyte count among the SS children. Likewise, no significant association was detected between β^S-haplotypes and the frequency of acute chest syndrome episodes, blood transfusions, splenic sequestration, or cerebrovascular disease (high-risk/conditional transcranial Doppler ultrasonography or clinical stroke). A limited number of Sβ⁰-thalassemia children precluded valid analyses. Conclusions: The prevalence of β^S-haplotypes in this study is in agreement with the historical records of African slaves brought to the state of Minas Gerais. Furthermore, β^S-haplotypes CAR and Ben were not associated with any analyzed feature of children with sickle cell anemia.