A novel frequent BRCA1 recurrent variant c.5117G > A (p.Gly1206Glu) identified after 20 years of BRCA1/2 research in the Baltic region: cohort study and literature review.

BACKGROUND: Several recent studies in the Baltic region have found extended spectrum of pathogenic variants (PV) of the BRCA1/2 genes. The aim of current study is to analyze the spectrum of the BRCA1/2 PV in population of Latvia and to compare common PV between populations of the Baltic region. METHODS: We present a cohort of 9543 unrelated individuals including ones with cancer and unaffected individuals from population of Latvia, who were tested for three most common BRCA1 founder PV. In second line testing, 164 founder negative high-risk individuals were tested for PV of the BRCA1/2 using next generation sequencing (NGS). Local spectrum of the BRCA1/2 PV was compared with the Baltic region by performing a literature review. RESULTS: Founder PV c.5266dupC, c.4035delA or c.181 T > G was detected in 369/9543 (3.9%) cases. Other BRCA1/2 PV were found in 44/164 (26.8%) of NGS cases. Four recurrent BRCA1 variants c.5117G > A (p.Gly1706Glu), c.4675G > A (p.Glu1559Lys), c.5503C > T (p.Arg1835*) and c.1961delA (p.Lys654fs) were detected in 18/44 (41.0%), 5/44 (11.4%), 2/44 (4.5%) and 2/44 (4.5%) cases respectively. Additionally, 11 BRCA1 PV and six BRCA2 PV were each found in single family. CONCLUSIONS: By combining three studies by our group of the same cohort in Latvia, frequency of the BRCA1/2 PV for unselected breast and ovarian cancer cases is 241/5060 (4.8%) and 162/1067 (15.2%) respectively. The frequency of three "historical" founder PV is up to 87.0% (369/424). Other non-founder PV contribute to at least 13.0% (55/424) and this proportion probably will rise by increasing numbers of the BRCA1/2 sequencing. In relative numbers, c.5117G > A is currently the third most frequent PV of the BRCA1 in population of Latvia, overcoming previously known third most common founder variant c.181 T > G. In addition to three BRCA1 founder PV, a total of five recurrent BRCA1 and two recurrent BRCA2 PV have been reported in population of Latvia so far. Many of the BRCA1/2 PV reported in Latvia are shared among other populations of the Baltic region.

Deletions in metastatic colorectal cancer with chromothripsis.

AIM: In our previously reported study, we found a correlation between DNA massive fragmentation and increased progression free survival (PFS) in metastatic colorectal cancer (mCRC), but not overall survival. The aim of this study is to find overlapping deleted genome regions in selected mCRC patients with chromothripsis and detect possible cause of increased PFS, and find new genes or combinations, involved in colorectal cancer oncogenesis. Materials and Methods: 10 mCRC patients with chromothripsis receiving 5-fluorouracil, oxaliplatin, leucovorin (FOLFOX) first-line palliative chemotherapy between August, 2011 and October, 2012 were selected for this study. Microarray analysis was performed using the Infinium HumanOmniExpress-12 v1.0 formalin-fixed paraffin-embedded (FFPE) BeadChip kit (Illumina). BeadChip was scaned on HiScan (Illumina). Analysis was performed by GenomeStudio software (Illumina) and R version 3.1.2. Copy number variation and breakpoints on the chromosomes were analyzed using the DNA copy package. RESULTS: Eight deleted tumor suppressor genes (ROBO2, CADM2, FAT4, PCDH10, PCDH18, CDH18, TSG1, CTNNA3) and four deleted oncogenes (CDH12, GPM6A, ADAM29, COL11A1) were identified in more than half of patients. In 70% patients' deletion in COL11A1 was detected. Deletion of MIR1269, MIR4465, MIR1261 and MIR4490 in patients with longer time to progression was observed. Four patients (40%) with PFS over 14 months, presented with NRG3 deletion (oncogene, еpidermal growth factor receptor (EGFR) ligand) what could possibly decrease proliferation of cancer cells via decreasing EGFR activation. CONCLUSIONS: Multiple chromosomal deletions (MIR1269, NRG3, ADK) in mCRC patients with chromothripsis are associated with better response to first line palliative FOLFOX-type chemotherapy and increased PFS.

Impact of KRAS variant rs61764370 on breast cancer morbidity.

UNLABELLED: Low-penetrance gene variants and their combinations are topical study objects in breast cancer pathogenesis. Single nucleotide polymorphism rs61764370, localized in 3՛ UTR of KRAS gene, plays an important role in the development and progression of several cancers. The aim of our study was to determine the KRAS variant impact on breast cancer morbidity. PATIENTS AND METHODS: 2214 patients diagnosed with breast cancer and 861 healthy controls were screened for KRAS variant by RFLP method. Available clinical data were collected and processed using statistical analysis methods. Results of present study suggest the KRAS variant impact on breast cancer development risk in premenopausal women, but it has no effect on breast cancer prognosis. We did not observe any KRAS variant effect on breast cancer patient 10-year disease-specific survival rates.