Porphyria cutanea tarda, which translates to "late skin form," is a genetic skin condition that becomes apparent in adulthood. It is characterized by photosensitivity due to the accumulation of uroporphyrins in the urine, stemming from a lack of the enzyme uroporphyrinogen decarboxylase (UROD). This enzyme is crucial for heme production, which is a component of the oxygen-carrying pigment in blood. The disease is marked by blistering that can lead to ulceration on sun-exposed areas, particularly the face, ears, and the backs of the hands. Affected skin is often fragile and may exhibit excess pigmentation and hair growth.As the most prevalent type of porphyria, porphyria cutanea tarda exists in two clinical forms and one severe form. The familial form is inherited and affects both males and females across generations, with reduced UROD activity in all tissues. The more common sporadic form sees decreased UROD activity limited to the liver, often triggered by factors like alcohol consumption or exposure to certain substances. Liver damage of varying degrees is frequently observed.A more severe variant, hepatoerythropoietic porphyria (HEP), begins in infancy and is characterized by protoporphyrin build-up in red blood cells, with very low UROD activity in these cells. The UROD gene is located on chromosome 1p34, and various mutations, such as DNA base substitutions and deletions, have been identified. These mutations reduce enzyme activity, leading to either porphyria cutanea tarda or the recessively inherited HEP, the latter being the homozygous form of the familial type.Treatment primarily involves lowering iron levels through regular blood removal (phlebotomy), followed by the administration of hydroxychloroquine to achieve lasting remission.
