Several mouse mutants with craniorachischisis exhibit an abnormal, broadened morphology of the ventral midline of the neural plate at the stage and site of closure 1, as seen in Vangl2Lp/Lp [26], ScribCrc/Crc [16], Celsr1Crsh/Crsh (unpublished data) mutants and the Ptk7 gene trap allele [21]. The gene discussed is PTK7; the disease is craniorachischisis.