<b>Background and Clinical Significance:</b> Congenital erythropoietic porphyria (CEP), also known as Günther disease, is a rare autosomal recessive porphyria caused by a deficiency of uroporphyrinogen III synthase, leading to the accumulation of phototoxic type I porphyrins. This evidence concerns the gene UROS and Congenital erythropoietic porphyria.