Our long-term goal should be to make hiPSC-based drug discovery systems a reality. The modern field of tissue engineering has advanced considerably and, although the human brain is far more difficult to model than mechanical tissue, keeping this as our long-term goal will likely help us develop more mature and sophisticated human neuron differentiation protocols. Such hiPSC-based drug discovery systems are also already well on their way. In some cases, abnormal neurobiological phenotypes have already been reversed with existing drugs 74,176,177. It is likely that the predictive validity of this system will only increase as the neurons used become more sophisticated and more accurately representative of human neurons. Groups have exploited neurobiological phenotypes they found in patient-derived neurons to conduct high-throughput genetic screens for compensatory mutations and potential drug targets 176–180. In contrast, the majority of current subtype characterization for clinical trials is done almost entirely through notoriously imprecise clinical diagnostic criteria. Gene network and neurobiological analyses on hiPSC-derived neurodevelopmental models could be used instead to identify subtypes based on specific genes/pathways that are altered. Finally, another therapeutic avenue may
