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. This evidence concerns the gene PRKG1 and craniorachischisis.