RESUMEN
Pathogenic Variants (PV) in major cancer predisposition genes are only identified in approximately 10% of patients with Hereditary Breast and Ovarian Cancer (HBOC) syndrome. Next Generation Sequencing (NGS) leads to the characterization of incidental variants in genes other than those known to be associated with HBOC syndrome. The aim of this study was to determine if such incidental PV were specific to a phenotype. The detection rates of HBOC-associated and incidental PV in 1812 patients who underwent genetic testing were compared with rates in control groups FLOSSIES and ExAC. The rates of incidental PV in the PALB2, ATM and CHEK2 genes were significantly increased in the HBOC group compared to controls with, respective odds ratios of 15.2 (95% CI = 5.6-47.6), 9.6 (95% CI = 4.8-19.6) and 2.7 (95% CI = 1.3-5.5). Unsupervised Hierarchical Clustering on Principle Components characterized 3 clusters: by HBOC (P = 0.01); by ExAC and FLOSSIES (P = 0.01 and 0.02 respectively); and by HBOC, ExAC and FLOSSIES (P = 0.01, 0.04 and 0.04 respectively). Interestingly, PALB2 and ATM were grouped in the same statistical cluster defined by the HBOC group, whereas CHEK2 was in a different cluster. We identified co-occurrences of PV in ATM and BRCA genes and confirmed the Manchester Scoring System as a reliable PV predictor tool for BRCA genes but not for ATM or PALB2. This study demonstrates that ATM PV, and to a lesser extent CHEK2 PV, are associated with HBOC syndrome. The co-occurrence of ATM PV with BRCA PV suggests that such ATM variants are not sufficient alone to induce cancer, supporting a multigenism hypothesis.
Asunto(s)
Neoplasias de la Mama , Síndrome de Cáncer de Mama y Ovario Hereditario , Neoplasias Ováricas , Proteínas de la Ataxia Telangiectasia Mutada/genética , Proteína BRCA2/genética , Neoplasias de la Mama/diagnóstico , Neoplasias de la Mama/epidemiología , Neoplasias de la Mama/genética , Femenino , Predisposición Genética a la Enfermedad , Pruebas Genéticas , Síndrome de Cáncer de Mama y Ovario Hereditario/diagnóstico , Síndrome de Cáncer de Mama y Ovario Hereditario/epidemiología , Síndrome de Cáncer de Mama y Ovario Hereditario/genética , Humanos , Incidencia , Neoplasias Ováricas/diagnóstico , Neoplasias Ováricas/epidemiología , Neoplasias Ováricas/genéticaAsunto(s)
Neoplasias de la Mama , Inhibidores de Poli(ADP-Ribosa) Polimerasas , Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/genética , Proteína del Grupo de Complementación N de la Anemia de Fanconi/genética , Humanos , Inhibidores de Poli(ADP-Ribosa) Polimerasas/uso terapéuticoRESUMEN
Hereditary breast cancers account for up to 5-10 % of breast cancers and a majority are related to the BRCA1 and BRCA2 genes. However, many families with breast cancer predisposition do not carry any known mutations for BRCA1 and BRCA2 genes. We explored the incidence of rare large rearrangements in the coding, noncoding and flanking regions of BRCA1/2 and in eight other candidate genes--CHEK2, BARD1, ATM, RAD50, RAD51, BRIP1, RAP80 and PALB2. A dedicated zoom-in CGH-array was applied to screen for rearrangements in 472 unrelated French individuals from breast-ovarian cancer families that were being followed in eight French oncogenetic laboratories. No new rearrangement was found neither in the genomic regions of BRCA1/2 nor in candidate genes, except for the CHEK2 and BARD1 genes. Three heterozygous deletions were detected in the 5' and 3' flanking regions of BRCA1. One large deletion introducing a frameshift was identified in the CHEK2 gene in two families and one heterozygous deletion was detected within an intron of BARD1. The study demonstrates the usefulness of CGH-array in routine genetic analysis and, aside from the CHEK2 rearrangements, indicates there is a very low incidence of large rearrangements in BRCA1/2 and in the other eight candidate genes in families already explored for BRCA1/2 mutations. Finally, next-generation sequencing should bring new information about point mutations in intronic and flanking regions and also medium size rearrangements.