Interestingly, there are 3 genes which, when mutated, not only affect paraxial mesoderm production in the mouse [109, 292, 298] but also result in an NTD phenotype in the mouse. These are Cyp26, Noggin, and Fgfr1 [94, 109, 293]. The Wnt3a , Lef1/Tcf1 double null  and Raldh2  mutants also have defective paraxial mesoderm production, with an abnormal neural tube during neurulation. Whether or not the paraxial mesoderm plays a primary role in successful neurulation in these mutants remains unknown.