Coinheritance of α-Thalassemia Decreases the Risk of Cerebrovascular Disease in a Cohort of Children with Sickle Cell Anemia

Abstract

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.

Reply: Genetic polymorphisms and cerebrovascular disease in children with sickle cell anemia from Rio de Janeiro, Brazil

“…Finally, we agree that differences between the two studies 1,12 may be related to the study design, as well as to the sample size. With respect to CVD, we would like to emphasize…”

“…We thank Belisário and colleagues 1 for their interest in our study. We are open to further discussions on this relevant subject.…”

Alpha-thalassemia should be considered in the differential diagnosis of a child with anemia

“…Dessa forma, recomenda-se a combinação dos diferentes parâmetros, com o objetivo de aumentar a especificidade do diagnóstico de deficiência de ferro 2,3 . A escolha do parâmetro a ser utilizado deve levar em consideração as características inerentes ao indivíduo ou grupo populacional, a idade, a prevalência e severidade da deficiência de ferro, a incidência de doenças inflamatórias e infecciosas, a frequência de doenças hematológicas, o volume da amostra de sangue requerido, o custo e a complexidade da metodologia utilizada e a susceptibilidade a erros laboratoriais 2 .…”

Alpha-thalassemia protects against cerebrovascular disease in children with sickle cell anemia

“…Recently, Filho et al found that Bantu/Atypical β S -globin gene cluster haplotype (β S -haplotype) was associated with the occurrence of CVD, and alpha-thalassemia (α-thal) was not 2 . We also have studied the influence of β S -haplotype and α-thal on CVD in a cohort of 208 children with SCA from Minas Gerais state, Brazil, and published it in 2010 3,4 . In our experience, α-thal genotypes were significantly associated with reduction in CVD risk 4 .…”

“…We also have studied the influence of β S -haplotype and α-thal on CVD in a cohort of 208 children with SCA from Minas Gerais state, Brazil, and published it in 2010 3,4 . In our experience, α-thal genotypes were significantly associated with reduction in CVD risk 4 . This association has been previously described.…”