A deficiency in the enzyme δ-aminolevulinic acid dehydratase (ALAD) is primarily a genetic condition rooted in specific mutations. This enzyme deficiency is the underlying cause of a rare metabolic disorder known as ALAD-Deficiency Porphyria (ADP).
Genetic Basis of ALAD Enzyme Deficiency
The fundamental cause of ALAD enzyme deficiency lies in the genetic makeup of an individual:
- Gene Mutation: The deficiency is directly caused by a mutation in the ALAD gene. This gene contains the instructions for making the δ-aminolevulinic acid dehydratase (ALAD) enzyme. When the ALAD gene is mutated, it leads to the production of a non-functional or deficient ALAD enzyme.
- Autosomal Recessive Inheritance: ALAD-Deficiency Porphyria (ADP) is inherited as an autosomal recessive disorder. This means that an individual must inherit one copy of the abnormal ALAD gene from each parent to develop the condition. People who inherit only one mutated copy are typically carriers and do not show symptoms, as their single functional gene can produce enough enzyme.
Role of the ALAD Enzyme
The δ-aminolevulinic acid dehydratase (ALAD) enzyme is critical in the body's heme synthesis pathway. Heme is a vital component of hemoglobin, the protein in red blood cells that carries oxygen, and is also found in other important proteins like cytochromes.
Specifically, the ALAD enzyme is responsible for the second step in heme synthesis, where it converts two molecules of δ-aminolevulinic acid (ALA) into porphobilinogen (PBG). When this enzyme is deficient, δ-aminolevulinic acid (ALA) accumulates in the body, leading to the symptoms associated with ALAD-Deficiency Porphyria.
Key Takeaways on ALAD Deficiency Causes
| Causal Factor | Description |
|---|---|
| Genetic Origin | Mutation in the ALAD gene, which codes for the δ-aminolevolevulinic acid dehydratase enzyme. |
| Inheritance Pattern | Autosomal recessive; two copies of the mutated gene (one from each parent) are required for the disorder. |
| Direct Consequence | Deficiency of functional ALAD enzyme, leading to the accumulation of δ-aminolevulinic acid (ALA). |
