SOX2 and craniorachischisis: Indeed, the aortic arch abnormalities that are highly penetrant in Lp/Lp and in the Vangl2flox/flox; Sox2-Cre and Vangl2flox/flox; PGK-Cre mutants described here, may be secondary to these gross abnormalities in body form, as they are only observed in the presence of craniorachischisis.