generate a perfectly matching cell in culture. This might be impossible even from ES or iPS cells given that the 3-dimensional context neurons usually are exposed to might provide essential clues for their final phenotype that might be very difficult to mimic in vitro. The question thus arises how close the neurons will have to resemble cells in the brain in order to acquire meaningful and relevant results that will inform about pathophysiology of the disease brain. A pessimistic view would be that the disease pathology of the brain is way too complex and pathophysiological traits need to be studied in iN cells perfectly matching affected cell types. An optimistic view would be that perhaps even suboptimally specified iN cells might be informative of pathophysiological processes going on in the brain. Along these lines, we would like to note that mouse iN cells carrying a mutation in Neuroligin 4 associated with the development of autism spectrum disorders exhibited the exact same specific synaptic phenotype that was previously observed in the mouse brain [59]. But even if iN cells show different phenotypes than observed in certain neurons in the brain, the phenomenon might be useful to find therapeutics. It is possible
