CDK5RAP2 and microcephaly: Previous studies on brain organoids generated from pluripotent stem cell lines with defects in primary microcephaly specific genes including ASPM [37], CPAP [38], WDR62 [39] and CDK5RAP2 [40] suggested that a loss in NPCs was caused by their premature differentiation, not by apoptosis, that lead to depletion of the progenitor population [41–43].