EWSR1 and Ewing sarcoma: The GGAA-microsatellite of two critical upregulated EWS/FLI-targets in Ewing sarcoma (NR0B1 and CAV1) have been shown to be highly polymorphic in African and white European populations, with a predisposition for significantly larger GGAA-microsatellites in Africans, especially at the NR0B1 locus [12].