The dura mater originates from the mesoderm,[22], [23] and small defects in the dura mater play an important role in SEDAC pathology.[5] We propose that dura mater development is inhibited by FOXC2 mutations in the foetus, and that as a result, the arachnoid mater protrudes from the dural defect, forming an expanding cyst. Here, FOXC2 is linked to cyst.