Prediction of MLH1 and MSH2 mutations in Lynch syndrome.
BACKGROUND
Lynch syndrome is caused primarily by mutations in the mismatch repair genes MLH1 and MSH2.


OBJECTIVE
To analyze MLH1/MSH2 mutation prevalence in a large cohort of patients undergoing genetic testing and to develop a clinical model to predict the likelihood of finding a mutation in at-risk patients.


METHODS
Personal and family history were obtained for 1914 unrelated probands who submitted blood samples starting in the year 2000 for full gene sequencing of MLH1/MSH2. Genetic analysis was performed using a combination of sequence analysis and Southern blotting. A multivariable model was developed using logistic regression in an initial cohort of 898 individuals and subsequently prospectively validated in 1016 patients. The complex model that we have named PREMM(1,2) (Prediction of Mutations in MLH1 and MSH2) was developed into a Web-based tool that incorporates personal and family history of cancer and adenomas.


METHODS
Deleterious mutations in MLH1/MSH2 genes.


RESULTS
Overall, 14.5% of the probands (130/898) carried a pathogenic mutation (MLH1, 6.5%; MSH2, 8.0%) in the development cohort and 15.3% (155/1016) in the validation cohort, with 42 (27%) of the latter being large rearrangements. Strong predictors of mutations included proband characteristics (presence of colorectal cancer, especially > or =2 separate diagnoses, or endometrial cancer) and family history (especially the number of first-degree relatives with colorectal or endometrial cancer). Age at diagnosis was particularly important for colorectal cancer. The multivariable model discriminated well at external validation, with an area under the receiver operating characteristic curve of 0.80 (95% confidence interval, 0.76-0.84).


CONCLUSIONS
Personal and family history characteristics can accurately predict the outcome of genetic testing in a large population at risk of Lynch syndrome. The PREMM(1,2) model provides clinicians with an objective, easy-to-use tool to estimate the likelihood of finding mutations in the MLH1/MSH2 genes and may guide the strategy for molecular evaluation.
Balmaña
Judith
J
Population Sciences Division, Dana-Farber Cancer Institute, and Division of Gastroenterology, Boston, Mass 02115, USA.
Stockwell
David H
DH
Steyerberg
Ewout W
EW
Stoffel
Elena M
EM
Deffenbaugh
Amie M
AM
Reid
Julia E
JE
Ward
Brian
B
Scholl
Thomas
T
Hendrickson
Brant
B
Tazelaar
John
J
Burbidge
Lynn Anne
LA
Syngal
Sapna
S
D048868:Adaptor Proteins, Signal Transducing; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002352:Carrier Proteins / Q000235:genetics*; D015331:Cohort Studies; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics*; D005260:Female; D005820:Genetic Testing; D006801:Humans; D020407:Internet; D016013:Likelihood Functions; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D015999:Multivariate Analysis; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein / Q000235:genetics*; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics*; D011336:Probability
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C501486:MLH1 protein, human; D009687:Nuclear Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein