title: Characterization of new founder Alu-mediated rearrangements in MSH2 gene associated with a Lynch syndrome phenotype.
abstract: It has been reported that large genomic deletions in the MLH1 and MSH2 genes are a frequent cause of Lynch syndrome in certain populations. Here, a cohort has been screened and two new founder rearrangements have been found in the MSH2 gene. These mutations have been characterized by break point determination, haplotype analysis, and genotype-phenotype correlation. Mutations have been identified in the MLH1, MSH2, and MSH6 genes in 303 subjects from 160 suspected Lynch syndrome unrelated families. All subjects were tested using heteroduplex analysis by capillary array electrophoresis. Multiplex ligation-dependent probe amplification was used to detect rearrangements in mutation-negative index patients and confirmed by reverse transcriptase PCR. The break point of the deletions was further characterized by the array comparative genomic hybridization method. Immunohistochemical staining and microsatellite instability were studied in tumor samples. Hereditary nonpolyposis colorectal cancer-related phenotypes were evaluated. More than 16% (24 of 160) of the families had pathogenic mutations (8 MLH1, 15 MSH2, and 1 MSH6). Twelve of these families (50%) are carriers of a novel mutation. Seven of the 15 positive MSH2 families (47%) are carriers of a rearrangement. The exon 7 deletion and exon 4 to 8 deletion of MSH2 are new founder mutations. The segregation of a common haplotype, a similar phenotype, and anticipation effects were observed in these families. These findings will greatly simplify the diagnosis, counseling, and clinical care in suspected Lynch syndrome families and not just in specific geographic areas, so wide distribution may be explained by migration patterns.
authors.affiliation: Cancer Genetics Laboratory, IBGM-CSIC, University of Valladolid, Spain.
authors.forename: Lucia
authors.initials: L
authors.lastname: Pérez-Cabornero
authors.forename: Ester
authors.initials: E
authors.lastname: Borrás Flores
authors.forename: Mar
authors.initials: M
authors.lastname: Infante Sanz
authors.forename: Eladio
authors.initials: E
authors.lastname: Velasco Sampedro
authors.forename: Alberto
authors.initials: A
authors.lastname: Acedo Becares
authors.forename: Enrique
authors.initials: E
authors.lastname: Lastra Aras
authors.forename: Jorge
authors.initials: J
authors.lastname: Cuevas González
authors.forename: Marta
authors.initials: M
authors.lastname: Pineda Riu
authors.forename: Teresa
authors.initials: T
authors.lastname: Ramón y Cajal Asensio
authors.forename: Gabriel
authors.initials: G
authors.lastname: Capellá Munar
authors.forename: Cristina
authors.initials: C
authors.lastname: Miner Pino
authors.forename: Mercedes
authors.initials: M
authors.lastname: Durán Domínguez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020087:Alu Elements / Q000235:genetics*; D001483:Base Sequence; D016022:Case-Control Studies; D015331:Cohort Studies; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics*; D055028:Comparative Genomic Hybridization; D004247:DNA / Q000235:genetics; D004252:DNA Mutational Analysis; D005091:Exons / Q000235:genetics; D005260:Female; D018703:Founder Effect; D015321:Gene Rearrangement; D056726:Genetic Association Studies; D018095:Germ-Line Mutation / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D008969:Molecular Sequence Data; D051718:MutS Homolog 2 Protein / Q000235:genetics* / Q000378:metabolism; D010375:Pedigree; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017384:Sequence Deletion; D012689:Sequence Homology, Nucleic Acid; D055815:Young Adult
chemical_list: D012333:RNA, Messenger; D004247:DNA; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein