Method for diagnosing familial adenomatous polyposis, characterized by the steps: determining the expression of at least one protein selected from the group consisting of RNF 115 (ring finger protein 115), HSPA8 (HSP70 protein 8), HSPD1 (HSP60 chaperonin), ASTN2 (astrotactin 2 isoform d), KRT9 (keratin 9), KRT10 (keratin 10), UQCRC1 (Ubiquinol-cytochrom c reductase core protein I), CCT5 (chaperonin containing TCP1 subunit 5 (epsilon)), NDUFS1 (NADH dehydrogenase Fe-S protein I), ACTB (actin, beta), LMNA (lamin A/C), ACY1 (aminoacylase 1), RUVBL1 (RuvB-like 1), CSTF2T (cleavage stimulation factor), TIGD5 (tigger transposable element derived 5), ECH1 (Enoyl coenzyme A hydratase 1), ALDH2 (aldehyd-dehydrogenase 2 family (mitoch.)) and KRT18 (keratin 18) in a tissue sample of a first individual; and comparing the expression of the at least one protein in a tissue sample of the first individual with the expression of the at least one protein in a tissue sample of a healthy second individual and/or of a third individual with sporadic colorectal carcinoma, wherein the presence of an increased expression of the at least one protein in the tissue sample of the first individual indicates the presence of familial adenomatous polyposis, and wherein the tissue sample is a sample of the intestinal mucosa; characterized in that the presence of an increased expression of ECH1 in a polyp and/or cancer cells of the first individual indicates the presence of familial adenomatous polyposis; and the presence of an increased expression of ALDH2 and/or KRT18 in cancer cells of the first individual indicates the presence of familial adenomatous polyposis. determining the expression of at least one protein selected from the group consisting of RNF 115 (ring finger protein 115), HSPA8 (HSP70 protein 8), HSPD1 (HSP60 chaperonin), ASTN2 (astrotactin 2 isoform d), KRT9 (keratin 9), KRT10 (keratin 10), UQCRC1 (Ubiquinol-cytochrom c reductase core protein I), CCT5 (chaperonin containing TCP1 subunit 5 (epsilon)), NDUFS1 (NADH dehydrogenase Fe-S protein I), ACTB (actin, beta), LMNA (lamin A/C), ACY1 (aminoacylase 1), RUVBL1 (RuvB-like 1), CSTF2T (cleavage stimulation factor), TIGD5 (tigger transposable element derived 5), ECH1 (Enoyl coenzyme A hydratase 1), ALDH2 (aldehyd-dehydrogenase 2 family (mitoch.)) and KRT18 (keratin 18) in a tissue sample of a first individual; and comparing the expression of the at least one protein in a tissue sample of the first individual with the expression of the at least one protein in a tissue sample of a healthy second individual and/or of a third individual with sporadic colorectal carcinoma, wherein the presence of an increased expression of the at least one protein in the tissue sample of the first individual indicates the presence of familial adenomatous polyposis, and wherein the tissue sample is a sample of the intestinal mucosa; characterized in that the presence of an increased expression of ECH1 in a polyp and/or cancer cells of the first individual indicates the presence of familial adenomatous polyposis; and the presence of an increased expression of ALDH2 and/or KRT18 in cancer cells of the first individual indicates the presence of familial adenomatous polyposis.