title: A unique pair of monozygotic twins with concordant clear cell renal cell carcinoma: a case report.
abstract: BACKGROUND
  Genetic predisposition to clear cell renal cell carcinoma (ccRCC) has been linked to disorders such as von Hippel-Lindau (VHL) syndrome. While twin research is a classic approach for elucidating genetic and environmental contributions to disease, no monozygotic twin-pair concordant for ccRCC in the absence of VHL syndrome has been previously reported in the literature or in major twin registries.
  
  
  METHODS
  We describe a unique monozygotic twin-pair concordant for ccRCC, with discordant but early ages of onset of 25 and 38 respectively. Cytogenetic studies and direct sequencing for VHL gene mutations in the second twin proved unremarkable.
  
  
  CONCLUSIONS
  This is the fi rst reported case of monozygotic twins concordant for ccRCC in the absence of VHL gene mutation. The early yet discordant, age of onset of disease in both twins suggests both genetic and environmental contributions to ccRCC.
authors.affiliation: Department of Medical Oncology, National Cancer Centre, Singapore. tan.min.han@nccs.com.sg
authors.forename: Min Han
authors.initials: MH
authors.lastname: Tan
authors.forename: Jasmine
authors.initials: J
authors.lastname: Yang
authors.forename: Hwei Ling
authors.initials: HL
authors.lastname: Tan
authors.forename: Chin Fong
authors.initials: CF
authors.lastname: Wong
authors.forename: Puay Hoon
authors.initials: PH
authors.lastname: Tan
authors.forename: Hong Gee
authors.initials: HG
authors.lastname: Sim
authors.forename: Peter
authors.initials: P
authors.lastname: Ang
authors.forename: Chee Keong
authors.initials: CK
authors.lastname: Toh
authors.forename: Miah Hiang
authors.initials: MH
authors.lastname: Tay
authors.forename: Eileen
authors.initials: E
authors.lastname: Poon
authors.forename: Aik Seng
authors.initials: AS
authors.lastname: Ooi
authors.forename: Bin Tean
authors.initials: BT
authors.lastname: Teh
mesh_terms: D000328:Adult; D002292:Carcinoma, Renal Cell / Q000235:genetics / Q000473:pathology*; D004200:Diseases in Twins / Q000235:genetics / Q000473:pathology*; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics / Q000473:pathology*; D008297:Male; D014430:Twins, Monozygotic; D006623:von Hippel-Lindau Disease / Q000235:genetics