(a) Human iPSCs are established from donor tissue of patients or healthy family controls. (b) Distinct brain region-specific organoids are then generated by patterning with proper morphogens based on the endogenous human brain development process using these hiPSCs. (c) Comparative analysis between patient and control organoids can be performed to reveal pathological phenotypes and mechanisms at molecular, cellular, structural, and functional levels. (d) Based on the knowledge acquired from these studies, brain region-specific organoids can be used for testing drug responses and large-scale drug screening. (e) Eventually, brain region-specific organoids can be used to develop novel and personalized therapeutic strategies for patients.