hormonal and metabolic disorders
Overview of Porphyrias
Introduction
Porphyrias are a group of disorders caused by deficiencies of enzymes involved in the production of heme. Hemeis a chemical compound that contains iron and gives blood its red color. Heme is a key component of several important proteins in the body. One of those proteins is hemoglobin, which enables red blood cells to carry oxygen. Heme is also an important part of certain enzymes made by the liver. Enzymes are special proteins produced by cells that speed up chemical reactions in the body. Heme is produced mainly in the bone marrow and liver through a complex process that requires eight different enzymes working in concert. The enzymes work one after another in separate steps that take the starting building blocks through several different intermediate compounds, finally producing heme. If there is a deficiency in one of these enzymes, certain intermediate compounds (porphyrin precursors) may accumulate. These may accumulate in the Bone marrow Liver Skin Other tissues Heme precursors may also appear in excess in the blood or be excreted in the urine or stool. The accumulated heme precursors cause symptoms and can often be detected by testing to help diagnose porphyria. The specific heme precursors that accumulate and the symptoms that develop depend on which enzyme is deficient. Porphyrias are a group of different disorders, each caused by a deficiency in one of the enzymes needed for heme production. Each enzyme deficiency is caused by an abnormality in the gene (a mutation) responsible for the production of the enzyme in question. The abnormal gene is almost always inherited from one of the parents or, rarely, both. 