Elder G H
Department of Medical Biochemistry, University of Wales College of Medicine, Cardiff, UK.
Semin Liver Dis. 1998;18(1):67-75. doi: 10.1055/s-2007-1007142.
Porphyria cutanea tarda (PCT) is a skin disease that results from decreased activity of uroporphyrinogen decarboxylase (UROD). About 80% of patients have the sporadic (type I) form in which UROD deficiency is restricted to the liver. Others have familial (type II) PCT in which mutations in the UROD gene are inherited in an autosomal dominant pattern with low clinical penetrance. PCT may also follow exposure to porphyrogenic chemicals. Clinically overt PCT (types I and II) is provoked by liver cell injury, particularly when associated with alcohol abuse, hepatitis C infection, or estrogens. Hepatic iron overload is common, depletion of iron stores produces remission, and their replenishment leads to relapse. In PCT, hepatic UROD is inactivated by a process targeted at its catalytic site, which is iron-dependent, requires a heme precursor, and may be accelerated by induction of cytochrome P450s. Susceptibility to develop PCT in response to common causes of liver injury may be determined by co-inheritance of genes that regulate components of this inactivation process.
迟发性皮肤卟啉症（PCT）是一种由于尿卟啉原脱羧酶（UROD）活性降低而导致的皮肤病。约80%的患者为散发型（I型），其中UROD缺乏仅限于肝脏。其他患者患有家族性（II型）PCT，其中UROD基因突变以常染色体显性模式遗传，临床外显率较低。PCT也可能在接触致卟啉化学物质后发生。临床上明显的PCT（I型和II型）由肝细胞损伤引发，尤其是与酒精滥用、丙型肝炎感染或雌激素相关时。肝铁过载很常见，铁储备耗竭会导致病情缓解，而补充铁则会导致复发。在PCT中，肝脏UROD通过针对其催化位点的过程而失活，该过程依赖铁，需要一种血红素前体，并且可能因细胞色素P450s的诱导而加速。对常见肝损伤原因产生PCT的易感性可能由调节该失活过程成分的基因共同遗传决定。
