The amino acid sequences of brown and black rat VKORC1 were downloaded from the nucleic sequences present at the NCBI GenBank (). Since brown (Rattus norvegicus, NP_976080) and black rat (Rattus rattus, XP_032748408) differed only in VKORC1 amino acid residue 90 (I or L, respectively), with similar hydrophobic side-chains, the brown rat VKORC1 sequence was selected for this study. To be 3D modeled, the spanish rat mutations S149I/T and E155K/Q and the prevalent Y139F resistance mutation, were introduced into the wild type VKORC1 amino acid sequence. The corresponding protein sequences were submitted to Sokrypton Colab Alphafold. ( /github/sokrypton/ColabFold/ blob/main/AlphaFold2.ipynb) . Similarities in Angstroms Å / number of common α-carbons, were in Root Square Mean Differences (RMSD)(Figure ).