The Natural History of Hb S/Hereditary Persistence of Fetal Hemoglobin in 13 Children from the State of Minas Gerais, Brazil.

Children with Hb S (HBB: c.20A > T)/hereditary persistence of fetal hemoglobin (Hb S/HPFH) have a mild clinical phenotype, but some complications have been reported. The natural history of Hb S/HPFH in children from the State of Minas Gerais, Brazil newborn cohort is described. Clinical and hematological data regarding participants' phenotypes were retrieved from medical records. The HPFH-1, HPFH-2, and HPFH-3 and α-thalassemia (α-thal) deletions were detected by gap-polymerase chain reaction (gap-PCR). Thirteen children were included, nine (69.2%) had the Hb S/HPFH-2 deletion, and four (30.8%) had Hb S/HPFH-1 deletion; 11 children (84.6%) had αα/αα, and two (15.4%) carried the αα/-α(3.7) (rightward) deletion. The mean concentration of total hemoglobin (Hb) and Hb F was 12.52 ± 0.56 g/dL and 42.31% ± 1.97%, respectively. Mild microcytosis and hypochromia were observed. We found acute clinical manifestations of sickle cell disease, such as acute chest syndrome (ACS) and acute pain crisis in four children; nine (69.2%) children were completely asymptomatic during the follow-up period. All children were classified as having low-risk transcranial Doppler (TDC). In conclusion, children with Hb S/HPFH have a mild clinical phenotype of sickle cell disease, although acute clinical manifestations may occur. High Hb F levels and absence of anemia are common hematological characteristics.