Southeast Asian ovalocytosis is a hereditary red blood cell disorder that is widespread in certain ethnic groups of Malaysia, Papua New Guinea, the Philippines, and Indonesia. Ovalocytic erythrocytes are rigid and exhibit reduced expression of many erythrocyte antigens. The ovalocytes are resistant to invasion in vitro by several strains of malaria, including Plasmodium falciparum and Plasmodium knowlesi (summary by Jarolim et al., 1991). The disorder is most often asymptomatic but has been reported to be associated with signs of mild hemolysis such as intermittent jaundice and gallstones (summary by Reardon et al., 1993). [from
OMIM]