A viral vector-delivered gene therapy can restore the activity of the AADC enzyme in people with AADC deficiency. This is the main results of an open-label Phase 1/2 trial that tested a gene therapy called AAV2-hAADC in eight young patients with AADC. AADC is caused by mutations in the gene DDC. These mutations render the body unable to make the aromatic L-amino acid decarboxylase enzyme, which is needed to make certain neurotransmitters, such as dopamine. The gene therapy was administered to all during a surgery, and it was injected into the putamen, a part of the brain particularly enriched with dopamine. The study demonstrated that AADC activity in the putamen of these patients increased substantially within six months of the gene therapy being administered. AADC activity in the putamen also remained high at two years post-therapy, the latest time point assessed.
