In the development of the brain and the differentiation of neurons, the transcriptional repressor Zinc Finger and BTB Domain Containing 18 (ZBTB18; formerly RP58) is essential, such as the deletion of RP58 leads to microcephaly, cerebellum hypoplasia, and corpus callosum agenesis in the mouse.21, 22. The gene discussed is ZBTB18; the disease is microcephaly.