For example, variants within the UROS promoter that disrupt the GATA1 or CP2-binding elements significantly reduce UROS transcription and cause a severe form of congenital erythropoietic porphyria (CEP), whereas other UROS promoter variants that do not disrupt these elements only cause a modest reduction in UROS transcription and mild cutaneous manifestations (Solis et al. 2001). The gene discussed is GATA1; the disease is Congenital erythropoietic porphyria.