The invisibility of sickle cell disease in Brazil: lessons from a study in Maranhão☆

Sickle cell disease (SCD) is a genetic disorder in which emoglobin S (Hb S) predominates in red blood cells. It is onsidered a significant public health issue in Brazil.1–3 Sickle cell anemia (SCA, Hb SS) is the most common subype of SCD in the world. Although its clinical course is ariable, patients with SCA generally have the most severe henotype. SCD also includes the heterozygous combination f Hb S with other hemoglobin variants (Hb SC, Hb SD-Punjab, nd others). The combination of Hb S with thalassemia (Hb / 0 and Hb S/ + thalassemia) leads to other subtypes of SCD ith a variable relative incidence depending on the ethnic omposition of the population.4,5 The relative death rate due to hemoglobin disorders in nder five-year-old children all over the world is reported to be .4% of all deaths.6 Morbidity and mortality are especially high n developing countries.7 Even in developed countries, SCD is till a significant cause of mortality, particularly in adolescents nd adults.8–10 There are only two newborn-screening cohort studies in razil, which have reported the death rate for children with CD. In both studies, it was very high compared to figures 3 eported in developed countries. In Minas Gerais, the crude eath rate for 1396 children (all subtypes) diagnosed in a even-year period was 5.6%. The Kaplan–Meier estimated robability of death at five years of age for children with Hb SS r Hb S/ 0 thalassemia was 10.6% (standard error: 1.4). In Rio