AAV-mediated gene therapy for rare metabolic disorders: turning a promise into a reality

Gene therapy is emerging as the realistic treatment option for inborn errors of metabolism (IEMs) and, with the promising safety and efficacy evidence from the proof-of-concept studies, adeno-associated virus (AAV) has become the frontrunner among viral vector candidates for these monogenic disorders. Different AAV capsids exhibit specific tissue tropisms, which can considerably increase the efficiency of gene transfer to particular organs. Here, we will discuss two distinct diseases: ornithine transcarbamylase (OTC) deficiency and Niemann–Pick disease type C, in which significant advances have been achieved in AAV-based gene therapy trials.