Fetal hemoglobin synthesis in sickle cell anemia: some molecular considerations

Effect of hydroxyurea on G gamma chain fetal hemoglobin synthesis by sickle-cell disease patients

Hydroxyurea is used for sickle-cell disease patients in order to increase fetal hemoglobin synthesis and consequently decrease the severity of pain episodes. Fetal hemoglobin, which is formed by gamma-globin chains A and G, is present in a constant composition throughout fetal development: about 75% of Ggamma and 25% of Agamma. In contrast, adult red cells contain about 40% of Ggamma and 60% of Agamma. In the present study, we analyzed the effect of hydroxyurea induction on the gamma chain composition of fetal hemoglobin in 31 sickle-cell disease patients treated with hydroxyurea. The control group was composed of 30 sickle-cell disease patients not treated with hydroxyurea in clinical steady state. The patients were older than 13 years and were not matched for age. All patients were seen at Hemocentro/UNICAMP and Boldrini Infantile Center, Campinas, SP, Brazil. The levels of total hemoglobin were significantly higher in patients treated with hydroxyurea (mean +/- SD, 9.6+/-2.16 g/dl) than in untreated patients (8.07+/-0.91 g/dl). Fetal hemoglobin levels were also higher in treated patients (14.16+/-8.31%) than in untreated patients (8.8+/-4.09%), as was the Ggamma/Agamma ratio (1.45+/-0.78 vs 0.98+/-0.4, P < 0.005). The increase in the Ggamma/Agamma ratio in patients treated with hydroxyurea suggests the prevalence of a pattern of fetal hemoglobin synthesis, whereas patients not treated with hydroxyurea maintain the adult pattern of fetal hemoglobin synthesis. Because no correlation was observed between the Ggamma/Agamma ratio and total hemoglobin or fetal hemoglobin levels, the increase in Ggamma chain synthesis may not imply a higher production of hemoglobin.

Stroke in Saudi children

This study reports the clinical features and neuroimaging correlates of stroke in Saudi children seen over a 5-year period at the King Fahd Hospital of the University, Al-Khobar, Saudi Arabia. During the study period, 31 (18 boys, 13 girls; mean age, 26.2 months) of the 20,895 children seen had stroke; the annual stroke incidence was 29.7 per 100,000 in the pediatric population. Ischemic strokes accounted for 90% and hemorrhagic 10% of the cases, respectively. The boys-to-girls ratio for ischemic stroke was 2:1. Cranial computed tomographic scans and magnetic resonance imaging findings were abnormal in 82% and 91%, respectively. The etiologic factor was undetermined in 65% of the cases. Our results suggest that stroke is uncommon in Saudi children. However, further studies evaluating a larger population in different clinical settings are required to provide a more comprehensive picture of stroke in children in this area.