Hereditary Spherocytosis


Hereditary Spherocytosis is an intrinsic hemolytic anemia caused by inherited defects in red blood cells (RBCs).

Hereditary Spherocytosis can be caused by autosomal dominant mutations in ankyrin, spectrin, band 3.1, or protein 4.2. These mutations lead to increased RBC fragility with loss of membrane blebs, and this loss of surplus membrane gives RBCs a spherical shape (instead of typical donut shape). The spleen may sequester and eliminate spherocytes, which causes a normocytic hemolytic anemia with jaundice and splenomegaly.

Labs show a typical hemolytic picture, with increased indirect bilirubin levels and increased reticulocyte count. Diagnosis can be confirmed by an osmotic fragility test. Treatment includes folate supplementation, although elective splenectomy is curative.

Find Hereditary Spherocytosis and other Autosomal Dominant Diseases among Pixorize's visual mnemonics for the USMLE Step 1 and NBME Shelf Exams.