These observations provide a better understanding of the underlying mechanisms that are involved in cortical thickness reduction in Dmrt5−/− embryos and of the microcephaly in human (De Clercq et al. 2018; Desmaris et al. 2018; Konno et al. 2012; Saulnier et al. 2013; Urquhart et al. 2016). Here, DMRTA2 is linked to microcephaly.