Southeast Asian ovalocytosis (SAO) is a rare hereditary red cell membrane defect characterized by the presence of oval-shaped erythrocytes and with most patients being asymptomatic or occasionally manifesting with mild symptoms such as pallor, jaundice, anemia and gallstones. The disease is Monarch Disease Ontology id MONDO_0008165 (southeast Asian ovalocytosis). Also known as: Melanesian elliptocytosis, Melanesian ovalocytosis, SAO, ovalocytosis, SA type, sao, stomatocytic elliptocytosis.