Civin W H, Epstein E
Ann Clin Lab Sci. 1980 Sep-Oct;10(5):395-401.
Heme is an important prosthetic group for proteins concerned with energy metabolism. All cells in the body probably make heme, but nucleated erythroid and hepatic cells have been studied the most. Feedback control of heme formation differs in the red cells and in the liver. About eight enzymes have a place in the formation of heme. Defects in the enzyme pathways may be the result of genetic abnormalities and phenotypically occur as hereditary porphyrias. If the major defect occurs in the red cell line, erythropoietic porphyrias occur; if the liver has the major defect, than hepatic porphyrias are present. There are probably three erythropoietic porphyrias and four hepatic porphyrias which are genetically determined. However, some are not clearly classified,--with erythropoietic protoporphyria involving hepatic and erythroid cells and porphyria cutanea tarda not being a clear cut genetic abnormality, at least some of the time. Elucidation of the genetic enzymatic defects introduces new diagnostic tools and also has led to at least one revolutionary new treatment for some hepatic porphyrias.
血红素是与能量代谢相关蛋白质的重要辅基。体内所有细胞可能都能合成血红素，但有核红细胞和肝细胞的相关研究最为深入。红细胞和肝脏中血红素形成的反馈控制有所不同。大约有八种酶参与血红素的形成过程。酶途径中的缺陷可能是由遗传异常导致的，在表型上表现为遗传性卟啉症。如果主要缺陷发生在红细胞系，则会出现红细胞生成性卟啉症；如果主要缺陷出现在肝脏，则会出现肝性卟啉症。可能有三种红细胞生成性卟啉症和四种肝性卟啉症是由基因决定的。然而，有些类型的卟啉症分类并不明确，例如红细胞生成性原卟啉症涉及肝细胞和红细胞，迟发性皮肤卟啉症至少在某些时候并非明确的遗传异常。对遗传酶缺陷的阐明引入了新的诊断工具，并且至少为一些肝性卟啉症带来了一种革命性的新疗法。
