Facteurs pronostiques de sévérité de la maladie drépanocytaire chez l'enfant.

Sickle cell anemia is a monogenic disease with a strikingly important variability in disease expression. Numerous studies over the last decades have attempted to track down predictors of severity to identify children at high risk of complications. Great diversity in study methodology or settings has precluded the identification of a robust and early predictor of severity in children. Three main markers have been extensively studied: HbF level, reticulocyte counts and the number of co-inherited alpha genes. HbF level is globally associated with a beneficial effect on disease severity, except for neurovascular complications. Reticulocyte count correlates with stroke risk or cerebral vasculopathy. Co inheritance of an alpha thalassemia trait (1 or 2 deleted alpha genes) is associated with a lower rate of neurovascular complication (excluding silent infarcts) but a higher rate of painful episodes. Cerebral velocities measured by transcranial Doppler are highly predictive of stroke risk in children. [ABSTRACT FROM AUTHOR]