Furthermore, conditional elimination of Shh expression in the mouse basal hypothalamus showed defects consistent with septo-optic dysplasia, similarly as observed in mice embryos lacking Sox3 and heterozygous for Sox2. Interestingly, Sox2 mutants exhibited a higher reduction of Shh and more severe defects in eyes, hypothalamus, and pituitary gland than mutants lacking Sox3. These results suggest that the range of decrease of Shh expression levels in the hypothalamus may correlate with the phenotypic variability exhibited in patients with septo-optic dysplasia (Zhao et al., 2012). This evidence concerns the gene SOX3 and Septo-optic dysplasia.