WNT1 and congenital hydrocephalus: Both Wnt1-Cre and Pax7−Cre drivers are robustly expressed in the embryonic neuroepithelium and both structural and molecular defects are present in utero (Figure 2, Figure 3 and Figure 4), and, as Pax3 expression mostly abates upon cell differentiation [32], the results of our study suggest that it is the specific absence of Pax3 that is instrumental in causing these congenital hydrocephalus phenotypes.