Each of the four authors of this book has a particular interest in disorders of porphyrin metabolism and special experience in their management. Their individual involvement in the field varies from 12 to 52 years and, combined, represents more than a century of personal experience. Since it has been written by both basic scientists and practicing physicians, the book is intended to be of value to all those involved in porphyrin metab- olism and the porphyrias. It is hoped that the fascination of porphyrin metabolism and the clinical challenge of the porphyrias experienced by each of the authors will be conveyed to the readers. Michael R. Moore Kenneth E. L. McColl Claude Rimington Abraham Goldberg vii CONTENTS Color Plates ...xvii 1. The History, Classification, and Incidence of the Porphyrias 1 1.1. History ...1 1.1.1. Early Chemistry ...2 1.1.2. Early Descriptions of Porphyria ...4 1.1.3. Biochemical Developments ...4 1.1.4. Acute Porphyria ...7 1.1.5. A Complete Pathway ...8 1.2. Classification of the Porphyrias ...9 1.2.1. The Current Classification...12 ...