Hemoglobin S disease

A hemoglobinopathy. Homozygous (Hb-SS) is sickle cell disease (symptomatic) and heterozygous is Sickle cell trait (Usually asymptomatic). Hemoglobin S is the result of a mutation that changes the Glutamic acid (hydrophilic) residue on the Beta chain into Valine (hydrophobic residue). The hydrophobic residue repels surrounding water and ultimately induces the deoxy hemoglobin molecules to polymerize, deforming the the red blood cell (sickle shaped).