Medical Genetics Rates of transitional and transversional substitutions(per site per 10 years)at nondegenerate, twofold degenerate, and fourfold degenerate codon sites Type of Twofold Fourfold substitution Nondegenerate degenerate degenerate Transition 040 2.24 Transversion 038 038 1.47 Total 0.78 2.24 371Medical Genetics