ALAD-Deficiency Porphyria (ADP)
What is δ-Aminolevulinic Acid Dehydratase Porphyria?
ADP is a severe disorder caused by a deficiency of the enzyme δ-aminolevulinic acid dehydratase (ALAD) which results in an increase of 5’-aminolevulinic acid (ALA) in the liver, other tissues, blood plasma, and urine. In addition, urine coproporphyrin and erythrocyte protoporphyrin are increased. ADP generally presents with sudden attacks of severe stomach pain that last for several days.
Who gets δ-Aminolevulinic Acid Dehydratase Porphyria?
All of the reported cases of ADP have been males, in contrast to the other acute porphyrias. ADP is the least common of all the porphyrias with less than 10 cases documented to date. This is an autosomal recessive disease, whereas the other three acute porphyrias are autosomal dominant. Each parent of an affected individual must have a mutation in one of their ALAD genes and both must pass their mutation on to their child.
What causes δ-Aminolevulinic Acid Dehydratase Porphyria?
ADP is caused by a deficiency of the enzyme δ-aminolevulinic acid dehydratase (ALAD).
How is δ-Aminolevulinic Acid Dehydratase Porphyria (ADP) diagnosed?
There are many laboratory tests available for the porphyrias, and it is often difficult to decide which should be chosen. Many of these tests are expensive and the results are often difficult to interpret. When abdominal and neurological symptoms suggest an acute porphyria, the best screening tests are urinary aminolevulinic acid (ALA) and porphobilinogen (PBG). DNA testing to identify the specific mutation in an individual’s porphyria-causing gene is the most specific and sensitive test to confirm the diagnosis of a specific porphyria. Before requesting DNA testing, it is recommended that patients have biochemical testing (urinary, stool and/or plasma porphyrins and porphyrin precursors (ALA and PBG) and/or enzyme assays). However, biochemical testing may be inconclusive.
- Also see FAQ: What diagnostic tests are available?
What are treatments for δ-Aminolevulinic Acid Dehydratase Porphyria?
Treatment is the same as in the other acute porphyrias. For the acute porphyrias, hospitalization is often necessary for acute attacks. Medications for pain, nausea and vomiting, and close observation are generally required with monitoring of salt and water balance. Harmful drugs should be stopped. Attacks are treated with either glucose loading or intravenous administration of hemin (Panhematin®). Attacks can be prevented in many cases by avoiding harmful drugs and adverse dietary practices.