The involvement of Ptch1 in cholesterol transport and the Ptch1-dependent Smo regulation mechanisms proposed in this study are consistent with the impairment of Hh signaling caused by decreased intracellular cholesterol levels that is observed in congenital malformations such as Smith-Lemli-Opitz syndrome (SLOS), desmosterolosis, and lathosterolosis [56]. Here, PTCH1 is linked to Smith-Lemli-Opitz syndrome.