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ALAD

ALAD

Aminolevulinate, delta-, dehydratase

What is the normal function of the ALAD gene?

The ALAD gene produces an enzyme called delta-aminolevulinate dehydratase. This enzyme is responsible for the second step in heme production. Heme is the portion of hemoglobin that carries oxygen in the blood from the lungs to the rest of the body. Each of the steps in heme production is controlled by a separate gene (see below). The enzyme made by ALAD normally produces a compound called porphobilinogen (PBG) from two molecules of delta-aminolevulinic acid. Porphobilinogen is eventually transformed by six other enzymes into heme.

The following genes are part of the chemical pathway for making heme.

  • ALAD:aminolevulinate, delta-, dehydratase
  • ALAS1:aminolevulinate, delta-, synthase 1
  • ALAS2:aminolevulinate, delta-, synthase 2 (sideroblastic/hypochromic anemia)
  • CPOX:coproporphyrinogen oxidase (coproporphyria, harderoporphyria)
  • FECH:ferrochelatase (protoporphyria)
  • HMBS:hydroxymethylbilane synthase
  • PPOX:protoporphyrinogen oxidase
  • UROD:uroporphyrinogen decarboxylase
  • UROS:uroporphyrinogen III synthase (congenital erythropoietic porphyria)

What conditions are related to the ALAD gene?

ALAD deficiency porphyria - caused by mutations in the ALAD gene

ALAD deficiency porphyria is caused by mutations in the ALAD gene that lead to changes in amino acids (the building blocks of proteins) in delta-aminolevulinate dehydratase. As a result, the enzyme becomes almost completely inactive, allowing a byproduct of heme production called aminolevulinic acid (ALA) to build up in the body.

Where is the ALAD gene located?

9q34

The ALAD gene is located on the long (q) arm of chromosome 9 at position 34.

The ALAD gene is located on the long (q) arm of chromosome 9 at position 34.

See How do geneticists indicate the location of a gene? in the Handbook.

Where can I find information about ALAD?

You and your healthcare professional may find the following resources about ALAD helpful.

  • Gene TestsThis link leads to a site outside Genetics Home Reference. - DNA tests ordered by healthcare professionals

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the ALAD gene or gene products?

  • ALA-Dehydrase
  • 5-aminolevulinate dehydratase
  • 5-Aminolevulinate hydro-lyase (adding 5-aminolevulinate and cyclizing)
  • Aminolevulinate dehydratase
  • Aminolevulinate Hydro-Lyase
  • Aminolevulinic Acid Dehydratase
  • delta-Aminolevulinate Dehydratase
  • delta-Aminolevulinic Acid Dehydratase
  • Porphobilinogen Synthase

See How are genetic conditions and genes named? in the Handbook.

Where can I find general information about genes?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding ALAD?

amino acid ; anemia ; compound ; congenital ; deficiency ; enzyme ; gene ; heme ; hemoglobin ; molecule ; mutation ; oxygen ; protein

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

 
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The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.
 
Last Comprehensive Review: June 2004
Updated: June 29, 2004
Published: October 8, 2004
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