Porphyria and porphyrinology--the past fifteen years.

The porphyrias are diseases caused by defective biosynthesis of heme. Leavened by digressions on porphyria trivia, this article presents selected highlights from the last 15 years of research on the chemistry, diagnosis, and treatment of the porphyrias. Thanks largely to genetic analysis and new light shed on the magical chemistry of heme biosynthesis, this period has seen great advances in the understanding of porphyria. Sequence analyses of the genes for all of the enzymes required for heme biosynthesis have revealed the porphyrias as highly heterogeneous, with multiple mutations underlying each type. As a result of technical advances, clinical porphyrin analyses are easier and more detailed, but their misapplication to "multiple chemical sensitivity syndrome" or "intoxication porphyria" is unfortunate. The prospect of gene therapy shines ever brighter but is neither safe nor effective enough to be considered for porphyria. As practical spin-offs, porphyrins are in use increasingly for diagnosis and treatment of cancer and as herbicides and pesticides. Accounts of alleged porphyria in "Prominent People" in the popular press continue to appear, generating fanciful misconceptions, often at the expense of patients with these fascinating diseases.