Cutaneous porphyria

An erythropoietic porphyria (massive accumulation of photoreactive porphyrins in the bone marrow erythroid cells and circulating erythrocytes, resulting in cutaneous photosensitivity) caused by biallelic variants in UROS (in an autosomal recessive inheritance pattern). Cases where biallelic variants reduce WT enzyme activity to <5% are characterized by photosensitivity, hemolytic anemia (often in utero), erythrodontia, splenomegaly, cutaneous blistering, scarring and disfigurement. Other cases where biallelic variants do not reduce enzyme activity as severely (5-12% of WT activity) have a later onset of photosensitivity and milder symptoms.