Elliptocytosis is a hematologic disorder characterized by elliptically shaped erythrocytes and a variable degree of hemolytic anemia. Inherited as an autosomal dominant, elliptocytosis results from mutation in any one of several genes encoding proteins of the red cell membrane skeleton.

The form discussed here is the one found in the 1950s to be linked to Rh blood group and more recently shown to be caused by a defect in protein 4.1. 'Rh-unlinked' forms of elliptocytosis are caused by mutation in the alpha-spectrin gene , the beta-spectrin gene , or the band 3 gene .Band 4.1 is a protein associated with the cytoskeleton of the red blood cell.