title: Clinical impact of molecular genetic diagnosis, genetic counseling, and management of hereditary cancer. Part II: Hereditary nonpolyposis colorectal carcinoma as a model.
abstract: Hereditary nonpolyposis colorectal carcinoma (HNPCC) is the most common hereditary form of colorectal carcinoma (CRC) and may account for 5-10% of the total CRC burden. The discovery of DNA mismatch repair (MMR) genes, inclusive of hMSH2, hMLH1, hPMS2, and hMSH6, has enabled the identification of who has and who does not have inordinately increased susceptibility to CRC as well as a litany of extracolonic cancers. Mutation testing has focused on hMSH2 and hMLH1, the most common mutations in HNPCC. The protocol for DNA testing and DNA-based genetic counseling is described in Part I of this study. One hundred ninety-nine bloodline relatives were tested and counseled from five hMLH1 and two hMSH2 families. Their major reason for seeking genetic counseling and DNA testing was to inform their children and other loved ones of their mutation status. Those who sought counseling overestimated their risk for inheriting the mutation and showed a high rate of interest in prophylactic surgery, and many were greatly concerned about insurance discrimination. Knowledge about HNPCC, its molecular genetic diagnosis, surveillance and management opportunities, and genetic counseling implications are still emerging, all in the face of a greater need for physician education regarding all facets of hereditary cancer.
authors.affiliation: Department of Preventive Medicine, Creighton University School of Medicine, Omaha, Nebraska 68178, USA.
authors.forename: H T
authors.initials: HT
authors.lastname: Lynch
authors.forename: P
authors.initials: P
authors.lastname: Watson
authors.forename: T G
authors.initials: TG
authors.lastname: Shaw
authors.forename: J F
authors.initials: JF
authors.lastname: Lynch
authors.forename: A E
authors.initials: AE
authors.lastname: Harty
authors.forename: B A
authors.initials: BA
authors.lastname: Franklin
authors.forename: C R
authors.initials: CR
authors.lastname: Kapler
authors.forename: S T
authors.initials: ST
authors.lastname: Tinley
authors.forename: B
authors.initials: B
authors.lastname: Liu
authors.forename: C
authors.initials: C
authors.lastname: Lerman
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002352:Carrier Proteins; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology / Q000601:surgery / Q000628:therapy; D003142:Communication; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; D005260:Female; D005817:Genetic Counseling; D005820:Genetic Testing; D018095:Germ-Line Mutation; D006117:Grief; D006167:Guilt; D006801:Humans; D008297:Male; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009363:Neoplasm Proteins / Q000235:genetics; D009687:Nuclear Proteins; D010817:Physician-Patient Relations; D011518:Proto-Oncogene Proteins / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein