title: Panel testing reveals nonsense and missense CDH1 mutations in families without hereditary diffuse gastric cancer.
abstract: BACKGROUND
  The reported penetrance of germline CDH1 mutations is high in families with hereditary diffuse gastric cancer (HDGC). Men and women have a 70% and 56%, respectively, cumulative risk of developing diffuse gastric cancer by age 80. Women additionally have a 42% cumulative risk of developing breast cancer. Due to the high penetrance of these mutations, prophylactic total gastrectomy is currently recommended for CDH1 mutation carriers. However, whether everyone with a CDH1 gene mutation is at risk for HDGC is not clear.
  
  
  METHODS
  Mutation identification was performed by next-generation sequencing. Mutations and variant status was confirmed by Sanger sequencing in 11 family members.
  
  
  RESULTS
  We present two families with pathogenic CDH1 mutations. The first family carries a novel truncating, nonsense CDH1 mutation that we were able to trace for three generations, but reports no family history of diffuse gastric cancer. The occurrence of cancer in this family deviates significantly from the expectation for HDGC. The proband from the second family presents with breast cancer and carries a previously reported pathogenic CDH1 mutation, but also reports no family history of diffuse gastric cancer.
  
  
  CONCLUSIONS
  Our study demonstrates the need for further analysis of CDH1 mutation penetrance in order to better counsel asymptomatic CDH1 mutation carriers on preventative measures and general care.
authors.affiliation: Department of Molecular and Cellular Biology University of Arizona Tucson Arizona.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Huynh
authors.affiliation: Department of Medicine Center for Applied Genetics and Genomics and University of Arizona Cancer Center College of Medicine University of Arizona Tucson Arizona.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Laukaitis
keywords: Ataxia telangiectasia mutated; E‐cadherin; breast cancer risk; germline mutation; hereditary diffuse gastric cancer