Mutations in ANK1 (∼ 50%) are the most common cause of HS, followed by SPTB (∼ 20%), SLC4A1 (∼ 15%), EPB42 (∼ 10%), and SPTA1 (∼ 5%) mutations (Delaunay, 2002; Wang et al., 2015). The gene discussed is ANK1; the disease is histiocytic sarcoma.