Hereditary spherocytosis: from clinical to molecular defects

Abstract

Resistance and elastic deformability of red cells are due to a protein network (cytoskeleton) that laminates the lipid bilayer and to proteins that span the latter. All proteins are interconnected. Their structure as well as the structure of the corresponding genes are now well known. Hereditary spherocytosis (HS) is the most common hemolytic anemia due to a red cell membrane defect. It derives from alterations of the following genes: ANK1, EPB3, ELB42, SPTA1 and SPTB. This condition is clinically, biochemically and genetically heterogeneous. The osmotically fragile spherocytes are selectively trapped in the spleen and destroyed. Increased red blood cell destruction causes the three main clinical signs of HS: anemia, jaundice and splenomegaly. In this review we analyze the most recent advances concerning the molecular basis and the clinical course of HS. In particular, we examine the major individual proteins that constitute the skeleton, which are now known to play an essential role in the pathogenesis of HS. This paper also includes a review of the therapeutical approach to HS. Concerning the diagnosis we provide a flow chart from the clinical aspects to the molecular diagnosis.