PPARG and Crouzon syndrome-acanthosis nigricans syndrome: Polymorphisms rs2737029 of the SNCA Gene, rs12149832 of the FTO Gene, rs1801282 of the PPARG GENE, rs13016963 of FLACC1 can be predisposition factors to the development of CAN, and resistance factors can be polymorphisms rs1108775 and rs1799782 of XRCC 1 gene.