The 22q11.2 deletion syndrome (22qDS) is the most common hemizygous microdeletion syndrome occurring in humans. Individuals with 22qDS show also a variety of neuro−anatomical defects.Our central hypothesis is that altered miRNAs biogenesis (caused by the hemizygous deletion of Dgcr8, one of the genes located in the 22q11.2 critical region, and required for miRNAs maturation) might impair embryonal/postnatal brain development, thus causing some of the defects observed in brains of 22qDS patients. Our working hypothesis is now further supported by the recent finding that aberrant embryonal neurogenesis is occurring in 22qDS mice and possibly in human patients. However a direct link between altered miRNAs biogenesis and aberrant neurogenesis in 22qDS is still missing.Interestingly, our preliminary results (obtained with hemizygous deletion of Dicer, a gene unrelated to 22qDS, but acting downstream Dgcr8 in the miRNAs maturation pathway) confirm and further expand the observation that reduction in miRNAs dosage affects preferentially the proliferation (or survival) of a basal neural progenitor cells in mice. Thus strengthening the hypothesis of an involvement of miRNAs in the 22qDS.In the current research proposal we aim to investigate whether altered maturation of miRNAs in brains of 22qDS mice, is affecting neurogenesis, and overall, the contribution of altered neurogenesis to the neuro−anatomical/pathological defects observed in 22qDS mice. We then plan to use induced pluripotent stem cells (iPS) from freshly collected fibroblasts of 22qDS patients, and reprogrammed toward neuronal progenitors lineages, in order to verify whether altered miRNAs biogenesis is contributing to some alterations also in a human cellular model of 22qDS.These achievements will allow the straightforward investigation of the cellular defects causing the disease, providing an optimal setting for future systematic drug screenings.