CELSR1 and craniorachischisis: In mice, among the numerous mouse gene mutations that cause NTDs, those that produce craniorachischisis are all components of the planar cell polarity pathway, including the PCP core factors, Vangl2, Celsr1, Dvl1/2/3 and Scrib; and the less central factors, Ptk7, Cdx1/2, Sec24b, Sfrp1/2/5 and Smurf1/2 [10].