In the 6 APC and MUTYH mutation negative cases with classical FAP phenotype, sequencing of the entire coding region of NTHL1 gene and the exonuclease domain of POLD1 gene (exons 6–13) and POLE gene (exons 9–14) did not identify any mutation. The gene discussed is NTHL1; the disease is Familial adenomatous polyposis.