ALA Dehydratase Deficiency Porphyria (ADP) is a rare genetic disorder that affects the body’s ability to produce heme, a component of hemoglobin. ADP is caused by a deficiency of the enzyme ALA dehydratase, which is responsible for converting the amino acid ALA into porphyrin. Symptoms of ADP include abdominal pain, nausea, vomiting, constipation, and dark urine. In severe cases, neurological symptoms such as seizures, confusion, and depression may occur. Treatment for ADP includes dietary changes, medications, and heme replacement therapy.