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New insights into POLE and POLD1 germline mutations in familial colorectal cancer and polyposis

2014; Oxford University Press; Volume: 23; Issue: 13 Linguagem: Inglês

10.1093/hmg/ddu058

1460-2083

Laura Valle, Eva Hernández‐Illán, Fernando Bellido, Gemma Aiza, Adela Castillejo, M.I. Castillejo, Matilde Navarro, Núria Seguí, Gardenia Vargas‐Parra, Carla Guarinós, Míriam Juárez, Xavier Sanjuán, Sílvia Iglesias, Cristina Alenda, Cecilia Egoavil, Ángel Segura, María-José Juan, María Rodríguez‐Soler, Joan Brunet, Sara González, Rodrigo Jover, Conxi Lázaro, Gabriel Capellá, Marta Pineda, José Luís Soto, Ignacio Blanco,

Cancer Genomics and Diagnostics

Germline mutations in DNA polymerase ɛ (POLE) and δ (POLD1) have been recently identified in families with multiple colorectal adenomas and colorectal cancer (CRC). All reported cases carried POLE c.1270C>G (p.Leu424Val) or POLD1 c.1433G>A (p.Ser478Asn) mutations. Due to the scarcity of cases reported so far, an accurate clinical phenotype has not been defined. We aimed to assess the prevalence of these recurrent mutations in unexplained familial and early-onset CRC and polyposis, and to add additional information to define the clinical characteristics of mutated cases. A total of 858 familial/early onset CRC and polyposis patients were studied: 581 familial and early-onset CRC cases without mismatch repair (MMR) deficiency, 86 cases with MMR deficiency and 191 polyposis cases. Mutation screening was performed by KASPar genotyping assays and/or Sanger sequencing of the involved exons. POLE p.L424V was identified in a 28-year-old polyposis and CRC patient, as a de novo mutation. None of the 858 cases studied carried POLD1 p.S478N. A new mutation, POLD1 c.1421T>C (p.Leu474Pro), was identified in a mismatch repair proficient Amsterdam II family. Its pathogenicity was supported by cosegregation in the family, in silico predictions, and previously published yeast assays. POLE and POLD1 mutations explain a fraction of familial CRC and polyposis. Sequencing the proofreading domains of POLE and POLD1 should be considered in routine genetic diagnostics. Until additional evidence is gathered, POLE and POLD1 genetic testing should not be restricted to polyposis cases, and the presence of de novo mutations, considered.