Treating a patient with ADP porphyria through suppression of both hepatic and erythroid ALA production.

δ-Aminolevulinic acid dehydratase deficient porphyria (ADP) is an exceedingly rare form of acute porphyria, with only fifteen published cases worldwide. This disorder has historically been considered an hepatic porphyria, as it was thought the overproduction of the toxic metabolite δ-Aminolevulinic acid (ALA) solely occurred in the liver. This case report demonstrates that treatments focused on reducing the hepatic ALA production had limited effect on this patient's symptoms. An earlier published hypothesis that patients with ADP also produce substantial levels of bone marrow derived ALA, was retested. We describe a Dutch patient in his early 60s, who has suffered from ADP since birth. His medical history mentions acute neurovisceral attacks, contractures of hand and feet, severe polyneuropathy, developmental delay, and renal insufficiency (eGFR 30-40 ml/min). For over a decade he was treated with weekly heme prophylaxis to reduce the frequency of neurovisceral attacks. Despite continuation, his chronic neurological symptoms aggravated and, in an attempt to suppress erythroid ALA production, weekly erythrocyte transfusions combined with hydroxyurea was started. The patient's symptoms improved and stabilized during this treatment. Oral chelation therapy was started to limit secondary iron overload caused by both heme and erythrocyte infusions. Years later we could trial givosiran, an ALAS1-siRNA to suppress the hepatic ALA production. After starting givosiran the heme infusions could be stopped without an increase in symptoms, but discontinuation of erythrocyte transfusions led to new onset neurovisceral attacks. His current schedule consists of continued givosiran and erythrocyte transfusions. This case report illustrates that ADP can be treated successfully with both hepatic and erythroid suppression. It also illustrates the challenges of treating a patient with a rare, complex and poorly understood disease, and the difficulty to balance the complications, side effects and the benefits of treatments.