An G-to-A mutation at 46,222,615 bp of chromosome 11 (GRCm38) occurred between 1961 and 1974 in the C57BL/6N strain that resulted in the amino acid substitution of serine with phenylalanine at position 968 (p.S968F). This mutation is found in all C57BL/6N substrains (C57BL/6NCrl, C57BL/6NTac and C57BL/6NJ) but is not present in the C57BL/6J strain or substrains (C57BL/6Ei, C57BL/6EiJ, C57BL/6ByJ and C57BL/6By). The mutation destabilizes the protein leading to decreased half-life.