Aminolevulinic Acid Dehydratase (ALAD)

What’s covered?

Aminolevulinic Acid Dehydratase (ALAD) deficiency is a rare autosomal-recessive disorder in which the enzyme ALAD

does not function properly. It is found that this enzyme is responsible for the production of porphobilinogen, one of two main chemicals

required for making heme, a component of hemoglobin. Heme is also found in myoglobin, a protein that helps muscles store oxygen. While we offer ALAD tests, it is important to understand the broader implications of blood testing in our article on "Understanding blood tests".

Deficiency of ALAD is responsible for the development of acute neurovisceral attacks mainly characterized by neurological symptoms such as weakness and tingling in hands and feet, followed by characteristic skin rash usually appearing on exposed parts of face, shoulders, back etc. The neurological symptoms may disappear within few days, however the skin rash will continue to remain for a long period. The other symptoms of ALAD deficiency include vomiting, fever, irritability and abdominal pain.

In acute cases, acute attacks may be fatal due to progression from neurological complications like paralysis or respiratory failure into coma. The only treatment available presently is to alleviate the symptoms by decreasing buildup of toxins in the blood. The only preventive methods include screening of newborns and proper prenatal dieting if a family is known to be carrying this autosomal-recessive disorder, but as tests for ALAD deficiency are rarely performed, there are chances that many cases go undiagnosed which exposes these people to the risk of developing life-threatening attacks.

ALAD deficiency is one of the most serious forms of porphyria. Although it may be very severe, it’s extremely rare for ALAD deficiency to cause death in a person under 30 years old. However, permanent disability due to nerve damage caused by severe attacks is much more common. There are no specific treatment approaches; people with ALAD deficiency are treated by trying to stabilise the level of heme, because keeping it normal helps prevent attacks.

Aminolevulinic Acid Dehydratase deficiency is managed by symptomatic treatment with blood transfusion and hematinics. The most commonly used medications include pyridoxine, which converts temporary porphyria to the more severe chronic form; Phototherapy (light therapy); Vitamin E supplements; Hematinics such as iron and Fluoride supplements; Atropine to prevent respiratory failure. Antibiotics are not indicated in cases of acute porphyria due to the risk of exacerbating erythropoiesis, although it may be required for treatment of sepsis in patients with chronic porphyria.