title: An American founder mutation in MLH1.
abstract: Mutations in the mismatch repair genes cause Lynch syndrome (LS), conferring high risk of colorectal, endometrial and some other cancers. After the same splice site mutation in the MLH1 gene (c.589-2A>G) had been observed in four ostensibly unrelated American families with typical LS cancers, its occurrence in comprehensive series of LS cases (Mayo Clinic, Germany and Italy) was determined. It occurred in 10 out of 995 LS mutation carriers (1.0%) diagnosed in the Mayo Clinic diagnostic laboratory. It did not occur among 1,803 cases tested for MLH1 mutations by the German HNPCC consortium, while it occurred in three probands and an additional five family members diagnosed in Italy. In the U.S., the splice site mutation occurs on a large (∼4.8 Mb) shared haplotype that also harbors the variant c.2146G>A, which predicts a missense change in codon 716 referred to here as V716M. In Italy, it occurs on a different, shorter shared haplotype (∼2.2 Mb) that does not carry V716M. The V716M variant was found to be present by itself in the U.S., German and Italian populations with individuals sharing a common haplotype of 280 kb, allowing us to calculate that the variant arose around 5,600 years ago (225 generations; 95% confidence interval 183-272). The splice site mutation in America arose or was introduced some 450 years ago (18 generations; 95% confidence interval 14-23); it accounts for 1.0% all LS in the Unites States and can be readily screened for.
authors.affiliation: Human Cancer Genetics Program, Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Jerneja
authors.initials: J
authors.lastname: Tomsic
authors.forename: Sandya
authors.initials: S
authors.lastname: Liyanarachchi
authors.forename: Heather
authors.initials: H
authors.lastname: Hampel
authors.forename: Monika
authors.initials: M
authors.lastname: Morak
authors.forename: Brittany C
authors.initials: BC
authors.lastname: Thomas
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Raymond
authors.forename: Anu
authors.initials: A
authors.lastname: Chittenden
authors.forename: Hans K
authors.initials: HK
authors.lastname: Schackert
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Gruber
authors.forename: Sapna
authors.initials: S
authors.lastname: Syngal
authors.forename: Alessandra
authors.initials: A
authors.lastname: Viel
authors.forename: Elke
authors.initials: E
authors.lastname: Holinski-Feder
authors.forename: Stephen N
authors.initials: SN
authors.lastname: Thibodeau
authors.forename: Albert
authors.initials: A
authors.lastname: de la Chapelle
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics*; D000328:Adult; D000368:Aged; D000483:Alleles; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000453:epidemiology / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005260:Female; D020022:Genetic Predisposition to Disease; D005858:Germany / Q000453:epidemiology; D006239:Haplotypes; D006579:Heterozygote; D006801:Humans; D007438:Introns / Q000235:genetics; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D022821:RNA Splice Sites / Q000235:genetics*; D014481:United States / Q000453:epidemiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D022821:RNA Splice Sites; D000070957:MutL Protein Homolog 1