Sferocytose

Sferocytose, often referred to as hereditary spherocytosis in medical contexts, is a genetic hemolytic anemia characterized by the presence of sphere-shaped red blood cells (spherocytes) in the circulating blood. It results from defects in red blood cell membrane proteins that weaken the cytoskeleton and plasma membrane, reducing the cells’ surface-area-to-volume ratio and deformability. The most commonly affected proteins are ankyrin-1 (ANK1), spectrin subunits (SPTA1, SPTB), band 3 (SLC4A1), and protein 4.2 (EPB42). Most cases are autosomal dominant, with rare recessive forms.

Clinical features include varying degrees of hemolysis, reticulocytosis, jaundice, splenomegaly, and mild to moderate chronic anemia. Neonates may present with hyperbilirubinemia and jaundice; with age, pigment gallstones due to chronic hemolysis may occur.

Diagnosis relies on blood tests: complete blood count shows reticulocytosis and often increased mean corpuscular hemoglobin concentration (MCHC); peripheral smear reveals spherocytes; osmotic fragility testing or acidified glycerol lysis test may be positive; EMA binding test by flow cytometry is commonly used. A family history supports the diagnosis, and genetic testing can identify pathogenic variants in ANK1, SPTB, SPTA1, SLC4A1, and EPB42.

Management is tailored to severity. Mild cases may require folic acid supplementation and regular monitoring. Splenectomy is considered for severe, symptomatic disease in childhood after infection risk reduction, sometimes with partial or staged approaches. Vaccination against encapsulated organisms and patient education are essential due to infection risk after splenectomy. Prognosis is generally favorable with appropriate management, though lifelong follow-up may be needed and risks include aplastic crises with parvovirus B19 infection and post-splenectomy sepsis.