title: Rare key functional domain missense substitutions in MRE11A, RAD50, and NBN contribute to breast cancer susceptibility: results from a Breast Cancer Family Registry case-control mutation-screening study.
abstract: BACKGROUND
  The MRE11A-RAD50-Nibrin (MRN) complex plays several critical roles related to repair of DNA double-strand breaks. Inherited mutations in the three components predispose to genetic instability disorders and the MRN genes have been implicated in breast cancer susceptibility, but the underlying data are not entirely convincing. Here, we address two related questions: (1) are some rare MRN variants intermediate-risk breast cancer susceptibility alleles, and if so (2) do the MRN genes follow a BRCA1/BRCA2 pattern wherein most susceptibility alleles are protein-truncating variants, or do they follow an ATM/CHEK2 pattern wherein half or more of the susceptibility alleles are missense substitutions?
  
  
  METHODS
  Using high-resolution melt curve analysis followed by Sanger sequencing, we mutation screened the coding exons and proximal splice junction regions of the MRN genes in 1,313 early-onset breast cancer cases and 1,123 population controls. Rare variants in the three genes were pooled using bioinformatics methods similar to those previously applied to ATM, BRCA1, BRCA2, and CHEK2, and then assessed by logistic regression.
  
  
  RESULTS
  Re-analysis of our ATM, BRCA1, and BRCA2 mutation screening data revealed that these genes do not harbor pathogenic alleles (other than modest-risk SNPs) with minor allele frequencies>0.1% in Caucasian Americans, African Americans, or East Asians. Limiting our MRN analyses to variants with allele frequencies of <0.1% and combining protein-truncating variants, likely spliceogenic variants, and key functional domain rare missense substitutions, we found significant evidence that the MRN genes are indeed intermediate-risk breast cancer susceptibility genes (odds ratio (OR)=2.88, P=0.0090). Key domain missense substitutions were more frequent than the truncating variants (24 versus 12 observations) and conferred a slightly higher OR (3.07 versus 2.61) with a lower P value (0.029 versus 0.14).
  
  
  CONCLUSIONS
  These data establish that MRE11A, RAD50, and NBN are intermediate-risk breast cancer susceptibility genes. Like ATM and CHEK2, their spectrum of pathogenic variants includes a relatively high proportion of missense substitutions. However, the data neither establish whether variants in each of the three genes are best evaluated under the same analysis model nor achieve clinically actionable classification of individual variants observed in this study.
authors.forename: Francesca
authors.initials: F
authors.lastname: Damiola
authors.forename: Maroulio
authors.initials: M
authors.lastname: Pertesi
authors.forename: Javier
authors.initials: J
authors.lastname: Oliver
authors.forename: Florence
authors.initials: F
authors.lastname: Le Calvez-Kelm
authors.forename: Catherine
authors.initials: C
authors.lastname: Voegele
authors.forename: Erin L
authors.initials: EL
authors.lastname: Young
authors.forename: Nivonirina
authors.initials: N
authors.lastname: Robinot
authors.forename: Nathalie
authors.initials: N
authors.lastname: Forey
authors.forename: Geoffroy
authors.initials: G
authors.lastname: Durand
authors.forename: Maxime P
authors.initials: MP
authors.lastname: Vallée
authors.forename: Kayoko
authors.initials: K
authors.lastname: Tao
authors.forename: Terrell C
authors.initials: TC
authors.lastname: Roane
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Williams
authors.forename: John L
authors.initials: JL
authors.lastname: Hopper
authors.forename: Melissa C
authors.initials: MC
authors.lastname: Southey
authors.forename: Irene L
authors.initials: IL
authors.lastname: Andrulis
authors.forename: Esther M
authors.initials: EM
authors.lastname: John
authors.forename: David E
authors.initials: DE
authors.lastname: Goldgar
authors.forename: Fabienne
authors.initials: F
authors.lastname: Lesueur
authors.forename: Sean V
authors.initials: SV
authors.lastname: Tavtigian
mesh_terms: D017766:Acid Anhydride Hydrolases; D000328:Adult; D019943:Amino Acid Substitution; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics; D019313:BRCA1 Protein / Q000235:genetics; D024682:BRCA2 Protein / Q000235:genetics; D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics*; D016022:Case-Control Studies; D018797:Cell Cycle Proteins / Q000235:genetics*; D064447:Checkpoint Kinase 2 / Q000235:genetics; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000235:genetics; D045643:DNA Repair Enzymes / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D006801:Humans; D000076228:MRE11 Homologue Protein; D008875:Middle Aged; D020125:Mutation, Missense; D009687:Nuclear Proteins / Q000235:genetics*; D020033:Protein Isoforms / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D024682:BRCA2 Protein; C551750:BRCA2 protein, human; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C121766:MRE11 protein, human; C112156:NBN protein, human; D009687:Nuclear Proteins; D020033:Protein Isoforms; D064447:Checkpoint Kinase 2; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C578634:CHEK2 protein, human; D000076228:MRE11 Homologue Protein; D017766:Acid Anhydride Hydrolases; C112158:RAD50 protein, human; D045643:DNA Repair Enzymes