digest by EarI (1.5 μl, New England Biolabs, Beverly, MA, USA) using 10 μl of PCR product in a total volume of 20 μl for 4 h at 37°C. Samples were separated by electrophoresis on 10% polyacrylamide gels, and the C and G alleles were identified by direct visualization following ethidium bromide staining. 307 animals from the NIHAC colony were genotyped using this method.
