<prompt> True about familial adenomatous polyposis is?Also known as Lynch syndromeFAP gene is located on 5p21100 risk of malignancy in classical varietyMales are usual carriers  <response>: Ans. is c i.e., 100 risk of malignancy in classical variety Familial adenomatous polyposis FAP syndrome Familiar polyposis coli is an autosomal dominant condition affecting males and females equally It is also called as familial polyposis coli. It is caused by mutation in adenomatous polyposis coli gene located on long arm of chromosome 5 5q21. Risk of malignancy is 100, i.e. all patients develop colorectal carcinoma if left untreated. There are following subtypes of FAP :a Classic FAP syndrome: A minimum of 100 polyps adenomas are necessary for diagnosis of classic FAP.b Attenuated FAP: Fewer polyps are there around 30 with less risk of malignancy 50.c Gardner syndrome: It is an autosomal dominant condition, characterized by presence of multiple adenomatous polyps with desmoid tumor, osteomas, epidermoid cysts, lipomas, dental abnormalities and periampullary carcinoma.d Turcots syndrome: It is characterized by multiple adenomatous polyps with CNS tumors medulloblastoma glioblastoma. 