@entity2513 are macroscopically visible morphological changes of the mucosa that can develop focal @entity189 in the absence of surgical intervention. The successive molecular changes proposed to occur at different stages in the @entity2513 sequence were primarily based on DNA studies of exophytic, polypoid-type @entity652 . Not all colorectal lesions, however, display an exophytic phenotype and a presumed distinct @entity14 , the nonpolypoid @entity652 , was subsequently described as a precursor of @entity14 . The low incidence of @entity984 mutations in nonpolypoid @entity2513 reported previously suggested a different genetic basis for the transformation process in these lesions. We have pursued the identification of genetic changes in benign sporadic nonpolypoid @entity2513 in a selected Swedish @entity1 group with no family history of @entity14 . Mutation screening of the @entity1412 ( @entity1412 ), @entity984 , and @entity876 genes was conducted using the protein truncation test, heteroduplex-single-strand conformation polymorphism analysis, and denaturing gradient gel electrophoresis on PCR-amplified fragments. Fourteen mutations in the @entity1412 gene were characterized in 10/20 samples. Mutations in the @entity984 and @entity876 genes were identified in 3/57 and 4/51 @entity652 , respectively. The mutation frequencies and distribution of mutations in @entity1412 correlate with published data on exophytic @entity652 . The low mutation frequency of the @entity876 gene is consistent with the benign nature of the research material. @entity984 activation (an early event in polypoid @entity2513 ) apparently does not play a significant role in nonpolypoid @entity652 development but may result in the development of a polypoid configuration. Genes Chromosomes Cancer 27:202-208, 2000.

Somatic mutations of the XXXX , @entity984 , and @entity876 genes in nonpolypoid @entity2513 .

@entity1 :: ('9606', 'Species') :: ['patient'] @entity984 :: ('3845', 'Gene') :: ['KRAS'] @entity1412 :: ('MESH:D011125', 'Disease') :: ['adenomatous polyposis coli', 'APC'] @entity189 :: ('MESH:D002277', 'Disease') :: ['carcinoma'] @entity876 :: ('7157', 'Gene') :: ['TP53'] @entity14 :: ('MESH:D015179', 'Disease') :: ['colorectal neoplasm', 'colorectal cancer'] @entity652 :: ('MESH:D000236', 'Disease') :: ['adenomas', 'adenoma'] @entity2513 :: ('MESH:C563365', 'Disease') :: ['colorectal adenomas', 'Colorectal adenomas', 'adenoma-carcinoma']
@entity1412 :: (MESH:D011125,Disease) :: ['APC']
