Familial adenomatous polyposis is characterised by ail except:
A i.e. Autosomal recessive transmissionRef: Sabiston Textbook of Surgery, 20th edition, page 1366-1369 Explanation:Hereditary cancersFamily history, Young age at onset Presence of other specific tumors and defects FAP and HNPCCSporadic cancersAbsence of family history, older age 60 - 80 years Isolated lesions in colon or rectumSpecific mutation is present in all cells of affected individualsFamilial cancersGenetic polymorphisms, Gene modifiers and defects in TyKLifetime risk increases for members in families in which index case is youngand relative is closeFAMILIAL ADENOMATOUS POLYPOSIS - HEREDITARY CANCER SYNDROMEAPC gene 5q21Mutation leads to Increased beta catenin levels and Wnt signal activation Earliest phenotype is Aberrant crypt formation Germline, somatic mutations seen and polymorphismCLASSIC FAPATTENUATED FAPGARDNERS SYNDROMEMore than 100 adenomatous polyps in colorectumManifest by late second or early third decadeGermline APC truncation mutations from codon 1250 - 1464 Autosomal dominantMutations close to the 5' end of the geneFar less than 100 polyps Tendency to spare the rectumProfuse colonic polyps, Mesenteric desmoids Skull and Mandible osteomas Periampullary cancersExtraintestinal Manifestations of FAP - CHRPE, PTC, Medulloblastoma, Gastric fundic polyps.The average age at discovery of a new patient with FAP is 29 years.
Autosomal recessive transmission
More than 100 polyps in colorectal area
Polyps seen in duodenum
Extra intestinal manifestations are present
Small & Large Intestine