A DR1 (direct repeat) motif adjacent to these sites is bound by the direct repeat erythroid-definitive repressor complex containing TR2 and TR4 (two nuclear orphan receptors), although enforced expression of TR2/TR4 paradoxically enhances fetal hemoglobin synthesis in both murine adult erythroid (AE) cells and SCD model mice (17,18). The gene discussed is NR2C2; the disease is Schnyder corneal dystrophy.