Morphologically, HS is characterized by the presence of spherocytes in peripheral blood smear, and is generally due to variants in one of the five genes (SPTA1, SPTB, ANK1, SLC4A1, and EBP42), encoding α-spectrin, β-spectrin, ankyrin, band 3 (anion exchanger 1, AE1), and protein 4.2, respectively [4]. The gene discussed is SLC4A1; the disease is histiocytic sarcoma.