We established a high diagnostic yield (63.1%) for microcephaly in an unselected Chinese cohort and reported seven novel neurodevelopmental disorders /microcephaly candidate genes, which involved in cell cycle and division (PWP2), CDC42/RAC signaling related actin cytoskeletal organization (DOCK9, RHOF), neurogenesis (ELAVL3, PPP1R9B) and transcription regulation (IRF2BP1). The gene discussed is CDC42; the disease is microcephaly.