[Erythropoietic porphyria. Report of the 1st case in Costa Rica].

Erythropoietic porphyria also known as Gunther's disease is the result of a deficiency of the enzyme uroporphyrinogen III cosynthetase. This abnormality deviates the biosynthesis of the porphyrins towards the formation of isomers belonging to the series I. These molecules are not utilized for the synthesis of the hem group and therefore accumulate in the tissues and body fluids, giving rise to the clinical and chemical findings of the disease. The present work constitutes the first report of this unusual genodermatosis in costa Rica. The propositus, a 46 years old woman, presented since childhood, a picture characterized by skin phototoxicity associated to hypertrichosis, erythrodontia, bone reabsorptions, distrophy of the nails, splenomegaly and elimination of urine that turned dark when exposed to sunlight. The laboratory findings were consistent with hemolytic anemia and the study of porphyrin metabolism revealed very significant increases in the urinary excretion of uroporphyrin and coproporphyrin, while the urinary excretion of delta aminolevulinic and porphobilinogen were normal.