The @entity2198 ( @entity124 ) phenotype, frequently identified in @entity14 ( @entity14 ), also accounts for approximately 15% of sporadic @entity14 . @entity124 ( @entity124 ) occurs from the mutational inactivation of the DNA mismatch repair genes, i.e. @entity4311 and @entity6756 in @entity14 , as well as from epigenetic inactivation of @entity6756 in sporadic @entity14 . The mutator pathway including @entity124 , @entity6756 promoter methylation, and @entity4311 and @entity6756 mutation patterns were identified in 21 sporadic @entity14 @entity1 younger than 30 yr excluding @entity14 . More than half of @entity5 showed @entity124 , with five @entity124 and six @entity124 ( @entity124 ). Three of six @entity5 showed the @entity6756 promoter methylation and did not express the @entity6756 protein. On the other hand, all @entity124 and all @entity124 ( @entity124 ) @entity5 expressed both @entity4311 and @entity6756 proteins. Two novel mutations, i.e. a missense mutation in @entity6756 and a splice-site alteration in @entity4311 , were identified in two @entity1 respectively. Although mutator pathway was implicated in younger-age-onset @entity14 , many @entity5 appeared to evolve from different genetic events other than @entity4311 and @entity6756 mutations frequently identified in @entity14 .

Characterization of mutator pathway in younger-age-onset XXXX .

@entity1 :: ('9606', 'Species') :: ['patients'] @entity6756 :: ('4292', 'Gene') :: ['hMLH1'] @entity2198 :: ('MESH:D006316', 'Disease') :: ['high-frequency microsatellite instability'] @entity124 :: ('MESH:D053842', 'Disease') :: ['MSI-H', 'microsatellite stable', 'Microsatellite instability', 'MSI', 'microsatellite instability', 'low-frequency microsatellite instability', 'MSS', 'MSI-L'] @entity5 :: ('MESH:D009369', 'Disease') :: ['MSI-H tumors', 'tumors'] @entity4311 :: ('4436', 'Gene') :: ['hMSH2'] @entity14 :: ('MESH:D015179', 'Disease') :: ['colorectal cancers', 'hereditary nonpolyposis colorectal cancer', 'HNPCC', 'colorectal carcinogenesis', 'colorectal adenocarcinoma', 'colorectal tumors']
@entity14 :: (MESH:D015179,Disease) :: ['colorectal adenocarcinomas']
