FAP and Lynch syndrome: MAP has a phenotypic overlap with FAP, attenuated FAP, and Lynch syndrome; biallelic carriers have an 80% cumulative lifetime risk of CRC by age 70 years.10 In several studies, among patients with early-onset CRC (diagnosed before age 50 years) who tested negative for Lynch syndrome, 1% to 2% were biallelic carriers of the MYH mutation.11–13