An infant presents with mild anemia, jaundice, and splenomegaly. A complete blood count with differential reveals spherocytosis; the reticulocyte count is elevated. The parents state that several relatives have also suffered from a similar illness.The infant's condition is most likely caused by defective?
The infant is suffering from hereditary spherocytosis, a disease that can result from defective erythrocyte cytoskeletal proteins such as spectrin or ankyrin. Spectrin is a cytoskeletal protein in the erythrocyte that binds to the ankyrin/band 3 protein complex. It also binds to a protein 4.1/actin complex to form a stable suppoing cytoskeletal network just below the plasma membrane. This helps to maintain the biconcave shape of the cell. Defective spectrin can lead to a destabilization of this network and a tendency of the affected cells to assume a spherical shape and become osmotically fragile. Such cells often become trapped in the splenic cords, and are subsequently destroyed by phagocytes. This can lead to hemolytic anemia, jaundice and splenomegaly. Clathrin is a protein found on the cytoplasmic side of the plasma membrane. It is located within the coating of the so-called coated pits seen in electron micrographs of cells engaged in receptor-mediated endocytosis. Connexon is a protein found in gap junctions, usually aggregated around the aqueous pores within the junctional area. Dynein is an ATPase protein responsible for the interaction and sliding of microtubule doublets, resulting in the bending of cilia and flagella. Ref: Murray R.K. (2011). Chapter 52. Red & White Blood Cells. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.
Clathrin
Connexon
Dynein
Spectrin