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What is Familial adenomatous polyposis is characterized by all except and explain in detail?
Familial adenomatous polyposis (FAP) Is a rare, inherited condition caused by a defect in the adenomatous polyposis coli (APC) gene - located in 5q 21 chromosome. FAP is autosomal dominant- >50% chance of inheritance in family members Has > 100 adenomatous polyps 100% RISK of malignancy Polyp formation - by 15 yrs. 100% develop malignancy - by 40 yrs. TOC: Total proctocolectomy + ileal pouch-anal anastomosis (TPC + IPAA) M/C/C of death after TPC = Peri-ampullary Ca (polyps in duodenum - periampullary region) Two variants of FAP Gardner's syndrome Osteoma (mandible) Congenital hyperophy of the retinal pigmented epithelium (CHRPE) lesions Sebaceous cysts Benign lymphoid polyposis of ileum Desmoid tumors Supernumerary teeth Turcot's syndrome: Brain tumors Medulloblastoma - m/c associated with FAP Glioblastoma multiforme - m/c associated with HNPCC