Novel UROD mutation for porphyria cutanea tarda, type 2: a case report.

Abstract

Porphyria cutanea tarda (PCT) is usually caused by acquired defects in uroporphyrinogen decarboxylase (UROD) activity in the liver. This more common form of PCT is called type 1 PCT. Major known risk factors for PCT include iron overload, such as occurs due to mutations in HFE, associated with classical hereditary hemochromatosis, chronic hepatitis C infection, heavy alcohol use, tobacco use, and estrogen therapy. In addition, in about 25% of patients with PCT, namely, those with PCT type 2, an inherited partial defect in UROD activity is found. In such persons, this partial defect, which is found in all cells, including hepatocytes, red blood cells, and others, contributes to the development of biochemically and clinically active disease. Herein we describe salient features of a man in his eighth decade of life with onset of clinical PCT. Among risk factors were heavy alcohol and tobacco use. Genetic testing revealed a novel mutation in one of his alleles of the UROD gene, namely, c.224 G>C; p. Arg 75 Pro, and enzymatic testing revealed that red blood cell UROD activity was decreased by 50%. This mutation in the UROD gene is predicted to have a major effect on protein structure and function, confirmed by the 50% decrease in activity of the enzyme. The previously undescribed mutation in UROD, found in this man, namely, c.224 G>C; p. Arg 75 Pro is pathogenic.