HBB and autosomal dominant cerebellar ataxia: The sickle cell results from a point mutation (A>T) in the beta-globin gene, in which the amino acid glutamic acid is replaced by a valine in the sixth position of the beta-globin chain, originating a Hb molecule with altered physical and biochemical features.(1,7) The main clinical manifestations of SCA are due to chronic hemolytic anemia, vaso-occlusive phenomena, and acute splenic sequestration.