title: RNA-based analysis of BRCA1 and BRCA2 gene alterations.
abstract: Alterations in BRCA1 and BRCA2 genes account for a large proportion of hereditary breast and ovarian cancers. Mutations and variants of unknown pathological significance have been identified in both genes; however, most of them have been studied only at the genomic level, and their effect on mRNA expression remains unknown. We identified two BRCA1 and six BRCA2 splice site variants, and one BRCA2 alteration at exon 14. Our aim was to ascertain the effect on RNA processing of the variants still unclassified. We found that BRCA1 c.IVS11 + 1G>A, BRCA2 c.7252_7272delinsTG, BRCA2 c.IVS2 + 1G>A, BRCA2 c.IVS13-2A>G, BRCA2 c.IVS21 + 4A>G, and BRCA2 c.9345G>A lead to aberrant transcripts in lymphocytes. Five of these six splice site variants caused a complete inactivation of the mutant allele because they produced frameshift similar to previously described deleterious exonic variants. Therefore, we consider them to be true deleterious mutations, possibly associated with an increased lifetime risk of breast or ovarian cancer. BRCA1 c.IVS17 + 6C>G, BRCA2 c.IVS12-9del4, and BRCA2 IVS1-9del3 represent rare variants, not disrupting normal mRNA processing. The last two BRCA2 genetic variants had not been reported in the Breast Cancer Information Core BIC database.
authors.affiliation: Section of Genetic Oncology, Division of Surgical, Molecular and Ultrastructural Pathology, University of Pisa and Pisa University Hospital, Via Roma, Pisa, Italy.
authors.forename: Fabrizia
authors.initials: F
authors.lastname: Bonatti
authors.forename: Chiara
authors.initials: C
authors.lastname: Pepe
authors.forename: Mariella
authors.initials: M
authors.lastname: Tancredi
authors.forename: Grazia
authors.initials: G
authors.lastname: Lombardi
authors.forename: Paolo
authors.initials: P
authors.lastname: Aretini
authors.forename: Elisa
authors.initials: E
authors.lastname: Sensi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Falaschi
authors.forename: Giovanna
authors.initials: G
authors.lastname: Cipollini
authors.forename: Generoso
authors.initials: G
authors.lastname: Bevilacqua
authors.forename: Maria Adelaide
authors.initials: MA
authors.lastname: Caligo
mesh_terms: D017398:Alternative Splicing; D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics; D004252:DNA Mutational Analysis; D005260:Female; D019398:Genes, BRCA1; D024522:Genes, BRCA2; D018095:Germ-Line Mutation; D006801:Humans; D008297:Male; D010051:Ovarian Neoplasms / Q000235:genetics; D010375:Pedigree; D022821:RNA Splice Sites; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism; D017422:Sequence Analysis, DNA; D012984:Software
chemical_list: D022821:RNA Splice Sites; D012333:RNA, Messenger