Novel BRCA1 splice-site mutation in ovarian cancer patients of Slavic origin

Abstract

Mutations in breast cancer susceptibility gene 1 (BRCA1) lead to defects in a number of cellular pathways including DNA damage repair and transcriptional regulation, resulting in the elevated genome instability and predisposing to breast and ovarian cancers. We report a novel mutation LRG_292t1:c.4356delA,p.(Ala1453Glnfs*3) in the 12th exon of BRCA1, in the splice site region near the donor site of intron 12. It is a frameshift mutation with the termination codon generated on the third amino acid position from the site of deletion. Human Splice Finder 3.0 and MutationTaster have assessed this variation as disease causing, based on the alteration of splicing, creation of premature stop codon and other potential alterations initiated by nucleotide deletion. Among the most important alterations are frameshift and splice site changes (score of the newly created donor splice site: 0.82). c.4356delA was associated with two ovarian cancer cases in two families of Slavic origin. It was detected by next generation sequencing, and confirmed with Sanger sequencing in both cases. Because of the fact that it changes the reading frame of the protein, novel mutation c.4356delA p.(Ala1453Glnfs*3) in BRCA1 gene might be of clinical significance for hereditary ovarian cancer. Further functional as well as segregation analyses within the families are necessary for appropriate clinical classification of this variant. Since it has been detected in two ovarian cancer patients of Slavic origin, it is worth investigating founder effect of this mutation in Slavic populations.

New Approach for Detection of Normal Alternative Splicing Events and Aberrant Spliceogenic Transcripts with Long-Range PCR and Deep RNA Sequencing

“…RNA-based experiments are often performed in diagnostics laboratories in order to identify variants that cause RNA splicing impairment [ 19 , 20 , 21 , 22 ]. RT-PCR followed by capillary electrophoresis and Sanger sequencing are golden standards for determining variants spliceogenicity.…”

Genetic testing results in Slovenian male breast cancer cohort indicate the BRCA2 7806-2A > G founder variant could be associated with higher male breast cancer risk

“…In 55 MBC cases, genetic testing with next-generation sequencing (NGS) was performed on blood samples. Of these, 54 were tested using NGS of targeted panels Illumina’s TruSight Cancer Panel or TruSight Hereditary Cancer Panel [ 16 ]. Large intragenic deletions in BRCA1 and BRCA2 genes were detected from NGS data with copy number analysis using SeqNext v4.4.0 (JSI medical systems) or with multiplex ligation-dependent probe amplification (MLPA).…”

Identification of Spliceogenic Variants beyond Canonical GT-AG Splice Sites in Hereditary Cancer Genes

“…Patients referred to the germline genetic testing for hereditary cancer syndromes at the Cancer Genetics Clinic, Institute of Oncology Ljubljana, had undergone genetic counseling. In total, 732 patients underwent NGS panel testing using hybrid capture library preparation with TruSight Cancer or TruSight Hereditary Cancer Panel (Illumina, San Diego, CA, USA) enrichment oligos performed as described before [34][35][36]. VUS, classified according to ACMG/AMP criteria, identified in genes associated with the patient's phenotype and family history were evaluated for their impact on splicing using in silico prediction tools.…”