NEUROG2 and Schinzel-Giedion syndrome: To reconcile with the brain pathology described in SGS patients, which affects postmitotic neural cells in patients9,10, we generated cortical neurons carrying either SGS mutations or the corresponding corrected alleles, by forcing the expression of the pro-neural factor NEUROGENIN 2 in NPCs38 in a chemically defined medium39 (Fig. 7a).