National Organization for Rare Disorders, Inc. It is possible
that the main title of the report Porphyria is not the name you
expected. - Acute Intermittent Porphyria - Variegate Porphyria -
Hereditary Coproporphyria - Porphyria Cutanea Tarda - Congenital
Erythropoietic Porphyria - ALA-D Porphyria Porphyria is a group
of at least eight metabolic disorders that arise as a result of
a malfunction in one of the eight steps in the body's synthesis
of a complex molecule called heme. Heme is essential for the
transport of oxygen to cells in the body. If any step in the
synthesis of heme is blocked, an intermediate chemical
accumulates in the cell, resulting in oxygen depletion. Those
intermediate chemicals, known as porphyrins or porphyrin
precursors, are the substances of which heme is composed. There
are two general categories of porphyrias, those that affect the
skin and those that affect the nervous system. The former are
called cutaneous porphyrias. The latter are called acute
porphyrias. Because the symptoms