Prevalence of sickle cell disease and sickle cell trait in national neonatal screening studies

Abstract

Sickle cell anemia is the best known hereditary blood disorder; there are serious complications associated with the condition. Diagnosis and early intervention reduce morbidity and mortality. These benefits have resulted in the widespread use of newborn screening education programs. In Brazil, the National Neonatal Screening Program established by decree 822/01 included sickle cell disease in the list of diseases tested in the so called "heel prick test". Since then, national studies of the results of this program have been periodically published. To review the literature in order to assess the prevalence of sickle cell trait and sickle cell anemia from data of national neonatal screening studies on hemoglobin S (Hb S). A bibliographic review was carried out using the key words: sickle cell anemia & hemoglobinopathies & neonatal screening & Brazil in the Bireme and SciELO databases. Original Brazilian studies presenting data on prevalence of the sickle cell trait (Hb AS) and sickle cell anemia (Hb SS) based on neonatal screening for Hb S were analysed. Twelve original national studies were identified with prevalences varying from 1.1% to 9.8% for the sickle cell trait and from 0.8 to 60 per 100,000 live births for sickle cell disease in different Brazilian regions. Conclusion: Neonatal screening for Hb S is a very useful method to assess the prevalence of sickle cell trait (Hb AS) and sickle cell anemia (Hb SS) in Brazil. There is a heterogeneous distribution of this disease with the highest prevalence in the northeastern region and the lowest prevalence in the south.

A rapid, inexpensive and disposable point‐of‐care blood test for sickle cell disease using novel, highly specific monoclonal antibodies

“…In this case, the predictive value of the positive result would be only 57%, which may result in unnecessary treatment for a large number of individuals. In areas with <0.5% incidence of SCD births, such as regions of Brazil (Lervolino et al , 2011), the predictive value of the positive result of a test with 98.5% specificity would decrease to <25%. The specificity, sensitivity, and the predictive value of both positive and negative results of the HemoTypeSC ™ test in this study were 100%; further studies are needed to ascertain whether this accuracy can be approached when the test method is used in low-resource settings.…”

Congolese children with sickle cell trait may exhibit glomerular hyperfiltration: A case control study

“…3 In United States, the sickle cell trait varies from 7% to 10% among African descendants. [4][5][6][7][8][9] The higher concentration of this sickle cell trait is found in Africa, in the Mediterranean region and the Middle West. 10 sub-Saharan Africa accounts for about 64% of newborns trait carriers.…”

Spatial Distribution of Newborns With Sickle Cell Trait in Sergipe, Brazil

“…SCA is endemic in many regions where malaria is or was prevalent due to the protective nature of the carrier state 1 and where the proportion of African descendants is higher. 2 Throughout the American Continent, the distribution of HbS -more prevalent in populations along the eastern coast -closely matches the distribution of people of African descent. 3 In Brazil, SCA is more prevalent in the Northeast and three states of the Southeast region -São Paulo, Rio de Janeiro, and Minas Gerais.…”

“…Nevertheless, according to the Ministry of Health, SCT is present in approximately 5.3% of the population in Bahia -the state with the highest percentage. 2 Patients with SCT are everywhere in Northeastern Brazil. In the state of Sergipe, the prevalence of HbAS among blood donors is 4.1%.…”