ALAD

The ALAD gene provides instructions for the production of an enzyme called delta-aminolevulinate dehydratase. This enzyme is responsible for the second step in the production of heme, the iron-containing part of hemoglobin. Hemoglobin is the oxygen-carrying protein in red blood cells. Each step in heme production is controlled by a different enzyme, each of which is produced from a single gene. Delta-aminolevulinate dehydratase normally produces a compound called porphobilinogen (PBG) from two molecules of delta-aminolevulinic acid (ALA). Porphobilinogen is transformed by six other enzymes into heme. The heme molecule is incorporated into hemoglobin and packaged into red blood cells, or it is used in the liver for the production of certain liver enzymes.

porphyria - caused by mutations in the ALAD gene

Mutations in the ALAD gene are responsible for a form of porphyria called ALAD deficiency porphyria. Most of these mutations cause a change in building blocks (amino acids) that make up delta-aminolevulinate dehydratase. These mutations prevent sufficient activity of this enzyme, allowing a byproduct of heme production called aminolevulinic acid (ALA) to build up in the body. An accumulation of this toxic substance causes the signs and symptoms of this form of porphyria.

Low levels of delta-aminolevulinate dehydratase may also increase the risk of developing lead poisoning when a person is exposed to environmental lead.