The gene responsible for ADP is ALAD, and the abnormal enzyme is ALAD. In people with ALAD the activity of this enzyme is very low, and the compound ALA builds up and can cause symptoms similar to those seen in AIP.
ADP is more severe than the other AHPs and can present in childhood. It is extremely rare, with only ~10 cases reported worldwide. The long-term complications are not well known.
Due to its extreme rarity, there are not as many recommendations for management of ADP, but the same general measures as the other AHPs are being followed. However, Panhematin may not be as effective in ADP. Liver transplantation has not proven to be of definite benefit in ADP, but some reports indicate that “hypertransfusions” (chronic blood transfusion therapy), in addition to liver transplant may be effective.
Givlaari has not been tested in ADP and its effectiveness is unknown.
ADP is an autosomal recessive condition. Autosomal means that the defect is not on the chromosomes that determine sex, and recessive means that both copies of the gene have changes. Family members with only one copy with a change generally do not have symptoms.