VKORC1 and Axenfeld-Rieger syndrome: Resistance to ARs is mainly linked to single nucleotide polymorphisms (SNPs) found in the three exons of the Vkorc1 gene,5, 20 encoding the main subunit of the VKOR complex, which induce amino acidic substitutions conferring resistance to ARs by preventing a proper binding of the anticoagulant to the enzyme.20