The MRE11, RAD50, and NBN genes encode for the nuclear MRN protein complex, which senses the DNA double strand breaks and initiates the DNA repair. The MRN complex also participates in the activation of ATM kinase, which coordinates DNA repair with the p53-dependent cell cycle checkpoint arrest. Carriers of homozygous germline pathogenic variants in the MRN complex genes or compound heterozygotes develop phenotypically distinct rare autosomal recessive syndromes characterized by chromosomal instability and neurological symptoms. Heterozygous germline alterations in the MRN complex genes have been associated with a poorly-specified predisposition to various cancer types. Somatic alterations in the MRN complex genes may represent valuable predictive and prognostic biomarkers in cancer patients. MRN complex genes have been targeted in several next-generation sequencing panels for cancer and neurological disorders, but interpretation of the identified alterations is challenging due to the complexity of MRN complex function in the DNA damage response. In this review, we outline the structural characteristics of the MRE11, RAD50 and NBN proteins, the assembly and functions of the MRN complex from the perspective of clinical interpretation of germline and somatic alterations in the MRE11, RAD50 and NBN genes.

• Klíčová slova
• ATLD, DNA repair, MRE11, NBN, NBS, NBSLD, NGS, RAD50, TP53, hereditary cancer syndromes, variant interpretation,
• MeSH
• ATM protein genetika   metabolismus   MeSH
• DNA vazebné proteiny genetika   metabolismus   MeSH
• enzymy opravy DNA genetika   metabolismus   MeSH
• homologní protein MRE11 genetika   metabolismus   MeSH
• hydrolasy působící na anhydridy kyselin genetika   metabolismus   MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• lidé MeSH
• nádorové supresorové proteiny * genetika   MeSH
• oprava DNA genetika   MeSH
• proteiny buněčného cyklu * metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• ATM protein MeSH
• DNA vazebné proteiny MeSH
• enzymy opravy DNA MeSH
• homologní protein MRE11 MeSH
• hydrolasy působící na anhydridy kyselin MeSH
• jaderné proteiny MeSH
• nádorové supresorové proteiny * MeSH
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu * MeSH
• RAD50 protein, human MeSH Prohlížeč

Interindividual differences in DNA repair systems may play a role in modulating the individual risk of developing colorectal cancer. To better ascertain the role of DNA repair gene polymorphisms on colon and rectal cancer risk individually, we evaluated 15,419 single nucleotide polymorphisms (SNPs) within 185 DNA repair genes using GWAS data from the Colon Cancer Family Registry (CCFR) and the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), which included 8,178 colon cancer, 2,936 rectum cancer cases and 14,659 controls. Rs1800734 (in MLH1 gene) was associated with colon cancer risk (p-value = 3.5 × 10-6 ) and rs2189517 (in RAD51B) with rectal cancer risk (p-value = 5.7 × 10-6 ). The results had statistical significance close to the Bonferroni corrected p-value of 5.8 × 10-6 . Ninety-four SNPs were significantly associated with colorectal cancer risk after Binomial Sequential Goodness of Fit (BSGoF) procedure and confirmed the relevance of DNA mismatch repair (MMR) and homologous recombination pathways for colon and rectum cancer, respectively. Defects in MMR genes are known to be crucial for familial form of colorectal cancer but our findings suggest that specific genetic variations in MLH1 are important also in the individual predisposition to sporadic colon cancer. Other SNPs associated with the risk of colon cancer (e.g., rs16906252 in MGMT) were found to affect mRNA expression levels in colon transverse and therefore working as possible cis-eQTL suggesting possible mechanisms of carcinogenesis.

• Klíčová slova
• DNA repair, cancer susceptibility, colon cancer, genome-wide association studies, rectal cancer, single nucleotide polymorphisms,
• MeSH
• biologická variabilita populace genetika   MeSH
• DNA modifikační methylasy genetika   MeSH
• DNA vazebné proteiny genetika   MeSH
• dospělí MeSH
• enzymy opravy DNA genetika   MeSH
• genetická predispozice k nemoci * MeSH
• hodnocení rizik MeSH
• jednonukleotidový polymorfismus MeSH
• karcinogeneze genetika   MeSH
• kolon patologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• MutL homolog 1 genetika   MeSH
• nádorové supresorové proteiny genetika   MeSH
• nádory rekta genetika   patologie   MeSH
• nádory tračníku genetika   patologie   MeSH
• oprava DNA genetika   MeSH
• registrace statistika a číselné údaje   MeSH
• rektum patologie   MeSH
• senioři MeSH
• studie případů a kontrol MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• DNA modifikační methylasy MeSH
• DNA vazebné proteiny MeSH
• enzymy opravy DNA MeSH
• MGMT protein, human MeSH Prohlížeč
• MLH1 protein, human MeSH Prohlížeč
• MutL homolog 1 MeSH
• nádorové supresorové proteiny MeSH
• RAD51B protein, human MeSH Prohlížeč

The vast majority of patients with Nijmegen Breakage Syndrome (NBS) are of Slavic origin and carry a deleterious deletion (c.657del5; rs587776650) in the NBN gene on chromosome 8q21. This mutation is essentially confined to Slavic populations and may thus be considered a Slavic founder mutation. Notably, not a single parenthood of a homozygous c.657del5 carrier has been reported to date, while heterozygous carriers do reproduce but have an increased cancer risk. These observations seem to conflict with the considerable carrier frequency of c.657del5 of 0.5% to 1% as observed in different Slavic populations because deleterious mutations would be eliminated quite rapidly by purifying selection. Therefore, we propose that heterozygous c.657del5 carriers have increased reproductive success, i.e., that the mutation confers heterozygote advantage. In fact, in our cohort study of the reproductive history of 24 NBS pedigrees from the Czech Republic, we observed that female carriers gave birth to more children on average than female non-carriers, while no such reproductive differences were observed for males. We also estimate that c.657del5 likely occurred less than 300 generations ago, thus supporting the view that the original mutation predated the historic split and subsequent spread of the 'Slavic people'. We surmise that the higher fertility of female c.657del5 carriers reflects a lower miscarriage rate in these women, thereby reflecting the role of the NBN gene product, nibrin, in the repair of DNA double strand breaks and their processing in immune gene rearrangements, telomere maintenance, and meiotic recombination, akin to the previously described role of the DNA repair genes BRCA1 and BRCA2.

• MeSH
• detekce genetických nosičů MeSH
• dospělí MeSH
• efekt zakladatele * MeSH
• haplotypy MeSH
• jaderné proteiny genetika   MeSH
• kohortové studie MeSH
• lidé středního věku MeSH
• lidé MeSH
• mutace * MeSH
• oprava DNA MeSH
• poškození DNA MeSH
• proteiny buněčného cyklu genetika   MeSH
• rozmnožování genetika   MeSH
• syndrom Nijmegen breakage etnologie   genetika   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Slovenská republika MeSH
• Názvy látek
• jaderné proteiny MeSH
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu MeSH

Genetic variations in 3' untranslated regions of target genes may affect microRNA binding, resulting in differential protein expression. microRNAs regulate DNA repair, and single-nucleotide polymorphisms in miRNA binding sites (miRSNPs) may account for interindividual differences in the DNA repair capacity. Our hypothesis is that miRSNPs in relevant DNA repair genes may ultimately affect cancer susceptibility and impact prognosis.In the present study, we analysed the association of polymorphisms in predicted microRNA target sites of double-strand breaks (DSBs) repair genes with colorectal cancer (CRC) risk and clinical outcome. Twenty-one miRSNPs in non-homologous end-joining and homologous recombination pathways were assessed in 1111 cases and 1469 controls. The variant CC genotype of rs2155209 in MRE11A was strongly associated with decreased cancer risk when compared with the other genotypes (OR 0.54, 95% CI 0.38-0.76, p = 0.0004). A reduced expression of the reporter gene was observed for the C allele of this polymorphism by in vitro assay, suggesting a more efficient interaction with potentially binding miRNAs. In colon cancer patients, the rs2155209 CC genotype was associated with shorter survival while the TT genotype of RAD52 rs11226 with longer survival when both compared with their respective more frequent genotypes (HR 1.63, 95% CI 1.06-2.51, p = 0.03 HR 0.60, 95% CI 0.41-0.89, p = 0.01, respectively).miRSNPs in DSB repair genes involved in the maintenance of genomic stability may have a role on CRC susceptibility and clinical outcome.

• Klíčová slova
• 3′UTR polymorphisms, MRE11A, colorectal cancer risk and clinical outcomes, double-strand break repair (DSBR) genes, miRNA binding sites,
• MeSH
• 3' nepřekládaná oblast genetika   MeSH
• DNA opravný a rekombinační protein Rad52 genetika   MeSH
• dospělí MeSH
• genetická predispozice k nemoci MeSH
• genotyp MeSH
• homologní protein MRE11 genetika   MeSH
• jednonukleotidový polymorfismus * MeSH
• kolorektální nádory genetika   patologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mikro RNA genetika   MeSH
• míra přežití MeSH
• mladý dospělý MeSH
• nádorové biomarkery genetika   MeSH
• následné studie MeSH
• oprava DNA genetika   MeSH
• prognóza MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• studie případů a kontrol MeSH
• vazebná místa MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 3' nepřekládaná oblast MeSH
• DNA opravný a rekombinační protein Rad52 MeSH
• homologní protein MRE11 MeSH
• mikro RNA MeSH
• MRE11 protein, human MeSH Prohlížeč
• nádorové biomarkery MeSH
• RAD52 protein, human MeSH Prohlížeč