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There are more than 260 million people of Slavic descent worldwide, who reside mainly in Eastern Europe but also represent a noticeable share of the population in the USA and Canada. Slavic populations, particularly Eastern Slavs and some Western Slavs, demonstrate a surprisingly high degree of genetic homogeneity, and, consequently, remarkable contribution of recurrent alleles associated with hereditary diseases. Along with pan-European pathogenic variants with clearly elevated occurrence in Slavic people (e.g., ATP7B c.3207C>A and PAH c.1222C>T), there are at least 52 pan-Slavic germ-line mutations (e.g., NBN c.657_661del and BRCA1 c.5266dupC) as well as several disease-predisposing alleles characteristic of the particular Slavic communities (e.g., Polish SDHD c.33C>A and Russian ARSB c.1562G>A variants). From a clinical standpoint, Slavs have some features of a huge founder population, thus providing a unique opportunity for efficient genetic studies.

This study aimed to analyze clinical and regional factors influencing the distribution of actionable genetic alterations in a large consecutive series of colorectal carcinomas (CRCs). KRAS , NRAS and BRAF mutations, HER2 amplification and overexpression, and microsatellite instability (MSI) were tested in 8355 CRC samples. KRAS mutations were detected in 4137/8355 (49.5%) CRCs, with 3913 belonging to 10 common substitutions affecting codons 12/13/61/146, 174 being represented by 21 rare hot-spot variants, and 35 located outside the "hot" codons. KRAS Q61K substitution, which leads to the aberrant splicing of the gene, was accompanied by the second function-rescuing mutation in all 19 tumors analyzed. NRAS mutations were detected in 389/8355 (4.7%) CRCs (379 hot-spot and 10 non-hot-spot substitutions). BRAF mutations were identified in 556/8355 (6.7%) CRCs (codon 600: 510; codons 594-596: 38; codons 597-602: 8). The frequency of HER2 activation and MSI was 99/8008 (1.2%) and 432/8355 (5.2%), respectively. Some of the above events demonstrated differences in distribution according to patients' age and gender. In contrast to other genetic alterations, BRAF mutation frequencies were subject to geographic variation, with a relatively low incidence in areas with an apparently warmer climate (83/1726 (4.8%) in Southern Russia and North Caucasus vs. 473/6629 (7.1%) in other regions of Russia, p = 0.0007). The simultaneous presence of two drug targets, BRAF mutation and MSI, was observed in 117/8355 cases (1.4%). Combined alterations of two driver genes were detected in 28/8355 (0.3%) tumors ( KRAS / NRAS : 8; KRAS / BRAF : 4; KRAS / HER2 : 12; NRAS / HER2 : 4). This study demonstrates that a substantial portion of RAS alterations is represented by atypical mutations, KRAS Q61K substitution is always accompanied by the second gene-rescuing mutation, BRAF mutation frequency is a subject to geographical variations, and a small fraction of CRCs has simultaneous alterations in more than one driver gene.

Hereditary cancer syndromes (HCSs) are arguably the most frequent category of Mendelian genetic diseases, as at least 2% of presumably healthy subjects carry highly-penetrant tumor-predisposing pathogenic variants (PVs). Hereditary breast-ovarian cancer and Lynch syndrome make the highest contribution to cancer morbidity; in addition, there are several dozen less frequent types of familial tumors. The development of the majority albeit not all hereditary malignancies involves two-hit mechanism, i.e. the somatic inactivation of the remaining copy of the affected gene. Earlier studies on cancer families suggested nearly fatal penetrance for the majority of HCS genes; however, population-based investigations and especially large-scale next-generation sequencing data sets demonstrate that the presence of some highly-penetrant PVs is often compatible with healthy status. Hereditary cancer research initially focused mainly on cancer detection and prevention. Recent studies identified multiple HCS-specific drug vulnerabilities, which translated into the development of highly efficient therapeutic options., Competing Interests: Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article., (©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.)

The spectrum of BRCA1/2 mutations demonstrates significant interethnic variations. We analyzed for the first time the entire BRCA1/2 coding region in 340 Belarusian cancer patients with clinical signs of BRCA1/2-related disease, including 168 women with bilateral and/or early-onset breast cancer (BC), 104 patients with ovarian cancer and 68 subjects with multiple primary malignancies involving BC and/or OC. BRCA1/2 pathogenic alleles were detected in 98 (29%) women, with 67 (68%) of these being represented by founder alleles. Systematic comparison with other relevant studies revealed that the founder effect observed in Belarus is among the highest estimates observed worldwide. These findings are surprising, given that the population of Belarus did not experience geographic or cultural isolation throughout history., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Purpose: This study aimed to analyze changes in the plasma concentration of EGFR-mutated circulating tumor DNA (ctDNA) occurring immediately after the start of therapy with EGFR tyrosine kinase inhibitors (TKIs)., Methods: Serial plasma samples were collected from 30 patients with EGFR-driven non-small cell lung cancer before intake of the first tablet and at 0.5, 1, 2, 3, 6, 12, 24, 36 and 48 h after the start of the therapy. The content of EGFR alleles (exon 19 deletions or L858R) in ctDNA was measured by ddPCR., Results: ctDNA was detected at base-line in 25/30 (83%) subjects. Twelve (50%) out of 24 informative patients showed > 25% reduction of the ctDNA content at 48 h time point; all these patients demonstrated disease control after 4 and 8-12 weeks of therapy. The remaining 12 individuals showed either stable content of EGFR-mutated ctDNA (n = 5) or the elevation of ctDNA concentration (n = 7). 10 of 12 patients with elevated or stable ctDNA level achieved an objective response at 4 weeks, but only 5 of 10 evaluable patients still demonstrated disease control at 8-12 weeks (p = 0.032, when compared to the group with ctDNA decrease). The decline of the amount of circulating EGFR mutant copies at 48 h also correlated with longer progression-free survival (14.7 months vs. 8.5 months, p = 0.013)., Conclusion: Comparison of concentration of EGFR-mutated ctDNA at base-line and at 48 h after the start of therapy is predictive for the duration of TKI efficacy., (© 2022. The Author(s) under exclusive licence to Japan Society of Clinical Oncology.)

DNA from formalin-fixed paraffin-embedded (FFPE) tissues, which are frequently utilized in cancer research, is significantly affected by chemical degradation. It was suggested that approaches that are based on duplex sequencing can significantly improve the accuracy of mutation detection in FFPE-derived DNA. However, the original duplex sequencing method cannot be utilized for the analysis of formalin-fixed paraffin-embedded (FFPE) tissues, as FFPE DNA contains an excessive number of damaged bases, and these lesions are converted to false double-strand nucleotide substitutions during polymerase-driven DNA end repair process. To resolve this drawback, we replaced DNA polymerase by a single strand-specific nuclease P1. Nuclease P1 was shown to efficiently remove RNA from DNA preparations, to fragment the FFPE-derived DNA and to remove 5'/3'-overhangs. To assess the performance of duplex sequencing-based methods in FFPE-derived DNA, we constructed the Bottleneck Sequencing System (BotSeqS) libraries from five colorectal carcinomas (CRCs) using either DNA polymerase or nuclease P1. As expected, the number of identified mutations was approximately an order of magnitude higher in libraries prepared with DNA polymerase vs. nuclease P1 (626 ± 167/Mb vs. 75 ± 37/Mb, paired t -test p -value 0.003). Furthermore, the use of nuclease P1 but not polymerase-driven DNA end repair allowed a reliable discrimination between CRC tumors with and without hypermutator phenotypes. The utility of newly developed modification was validated in the collection of 17 CRCs and 5 adjacent normal tissues. Nuclease P1 can be recommended for the use in duplex sequencing library preparation from FFPE-derived DNA.

Whole exome sequencing (WES) is a powerful tool for the cataloguing of population-specific genetic diseases. Within this proof-of-concept study we evaluated whether analysis of a small number of individual exomes is capable of identifying recurrent pathogenic alleles. We considered 106 exomes of subjects of Russian origin and revealed 13 genetic variants, which occurred more than twice and fulfilled the criteria for pathogenicity. All these alleles turned out to be indeed recurrent, as revealed by the analysis of 1045 healthy Russian donors. Eight of these variants (NAGA c.973G>A, ACADM c.985A>C, MPO c.2031-2A>C, SLC3A1 c.1400T>C, LRP2 c.6160G>A, BCHE c.293A>G, MPO c.752T>C, FCN3 c.349delC) are non-Russian-specific, as their high prevalence was previously demonstrated in other European populations. The remaining five disease-associated alleles appear to be characteristic for subjects of Russian origin and include CLCN1 c.2680C>T (myotonia congenita), DHCR7 c.453G>A (Smith-Lemli-Opitz syndrome), NUP93 c.1162C>T (steroid-resistant nephrotic syndrome, type 12), SLC26A2 c.1957T>A (multiple epiphyseal dysplasia) and EIF3F c.694T>G (mental retardation). These recessive disease conditions may be of particular relevance for the Russian Federation and other countries with a significant Slavic population., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Purpose: This study aimed to investigate factors, which influence the content of circulating tumor DNA (ctDNA)., Methods: 398 serial plasma samples were collected within 1-7 consecutive days from patients with EGFR-mutated lung cancer (n = 13), RAS/RAF-mutated colorectal cancer (n = 54) and BRAF-mutated melanoma (n = 17), who presented with measurable tumor disease. The amount of ctDNA was determined by ddPCR., Results: Among 82 patients, who donated 2-6 serial plasma samples, 42 subjects were classified as ctDNA-positive; only 22% cases were mutation-positive across all consecutive tests, while 24/82 (29%) patients showed presence of mutated ctDNA in some but not all blood draws. Subjects with progressing tumors had higher probability of being detected ctDNA-positive as compared to patients, who responded to therapy or had stable disease (39/55 (71%) vs. 4/24 (17%); p = 0.0001). Our study failed to reveal the impact of the time of the day, recent meal or prior physical exercise on the results of ctDNA testing., Conclusions: Presence of ctDNA in plasma is particularly characteristic for patients, who experience clinical progression of tumor disease. Consecutive plasma tests may occasionally provide discordant data; thus, the repetition of analysis may be advised in certain cases in order to ensure the validity of negative ctDNA result., Competing Interests: Declaration of Competing Interest E. Kuligina, R.Meerovich, K. Zagorodnev, M. Kholmatov, T. Sokolova, T. Laidus, A. Romanko, A. Martianov, M. Anisimova, O. Zaitseva, O. Yatsuk, G. Yanus, and E. Imyanitov declare that they have no competing interests., (Copyright © 2021. Published by Elsevier Inc.)

Background: Many cancer patients undergo sophisticated laboratory testing, which requires proper interpretation and interaction between different specialists., Case Presentation: We describe a patient with an extensive family history of cancer, who was diagnosed with bilateral breast cancer and two lung cancer lumps by the age of 40 years. She submitted a lung cancer specimen to a genetic profiling service, which reported the presence of the EGFR mutation (a combination of G719S and L833V substitutions) and the TP53 с.322_327del (p.G108_F109del) mutation in the tumor tissue. Possible therapeutic options were discussed at a medical conference, where one of the discussants raised a concern that the identified TP53 mutation may not necessarily be somatic, but reflect the germ-line status of the gene. Review of clinical records and follow-up dialog with the patient revealed, that she previously provided her blood for DNA analysis in two laboratories. The first laboratory utilized a custom NGS assay and did not detect the TP53 mutation, instead pointed to a potential pathogenic significance of the MSH6 c.2633 T > C (p.V878A) allele. The second laboratory revealed the TP53 с.322_327del (p.G108_F109del) allele but stated in the written report that it has an unknown pathogenic significance. To resolve the possible uncertainty regarding the role of the TP53 с.322_327del (p.G108_F109del) variant, we suggested that the patient invite her second cousin for genetic testing, as she was affected by neuroblastoma at the age of 3 years. This analysis revealed the presence of the same TP53 variant., Conclusion: We provide point-by-point discussion, reviewing multiple laboratory mistakes and clinical misinterpretations occurred with this patient. This case report exemplifies the need to involve rigorous clinical expertise in the daily practice of medical laboratory facilities.

Alpha-chain collagen molecules encoded by genes that include COL11A1 are essential for skeletal, ocular, and auditory function. COL11A1 variants have been reported in syndromes involving these organ systems. However, a description of the complete clinical spectrum is lacking, as evidenced by a recent association of autosomal dominant nonsyndromic hearing loss due to a splice-altering variant in COL11A1, mapping the DFNA37 locus. Here, we describe two German families presenting prelingual autosomal dominant nonsyndromic hearing loss with novel COL11A1 heterozygous splice-altering variants (c.652-1G>C and c.4338+2T>C) that were molecularly characterized. Interestingly, the c.652-1G>C variant affects the same intron 4 canonical splice site originally reported in the DFNA37 family (c.652-2A>C) but elicits a different splicing outcome. Furthermore, the c.4338+2T>C variant originated de novo. We provide clinical and molecular genetic evidence to unambiguously confirm that COL11A1 splice-altering variants cause DFNA37 hearing loss and affirm that COL11A1 be included in the genetic testing of patients with nonsyndromic deafness., (© 2020 The Authors. Human Mutation published by Wiley Periodicals LLC.)

Colorectal carcinomas (CRCs) caused by hereditary biallelic MUTYH gene mutations are characterized by elevated mutation load and high lymphocyte infiltration. Given that these tumor features are associated with the response to immune checkpoint inhibitors, we administered nivolumab to a CRC patient who carried two inactive MUTYH alleles (p.Y179C and p.G396D) and previously experienced failure of chemotherapy. This experimental treatment resulted in a pronounced tumor response. We further compared tumor lymphocyte infiltration in MUTYH-associated (n = 3), high-level microsatellite instability (MSI-H, n = 8) and microsatellite stable (MSS, n = 6) CRCs. Both MUTYH-driven and MSI-H CRCs showed noticeably higher lymphocyte densities than those of microsatellite stable tumors; this difference reached the level of statistical significance for the comparison of central areas of the tumors (p = 0.02 and 0.03, respectively) but not for the invasive tumor margins. Although MUTYH-associated tumors are exceptionally rare among unselected CRC cases, their share in CRC patients with somatic KRAS p.G12C substitution approaches 5-25%. These observations provide a rationale for further evaluation of the efficacy of the immune checkpoint blockade in MUTYH-driven CRC.

Hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome (LS), is a common cancer-predisposing syndrome. This study aimed to investigate the spectrum of germ-line mutations in Russian LS patients. LS-related mismatch repair (MMR) genes were analyzed in 16 patients, who were forwarded to genetic testing due to strong clinical features of LS and had high-level microsatellite instability (MSI-H) in the tumor (n = 14) or unknown MSI status (n = 2). In addition, 672 consecutive colorectal cancer (CRC) cases were screened for family history; 15 patients were younger than 50 years and reported 2 or more instances of LS-related cancers in 1st- or 2nd-degree relatives. Seven of these cases demonstrated MSI-H and therefore were subjected to DNA germ-line testing. Overall, 17/23 (74%) subjects carried LS-associated gene variants (MLH1: 10; MSH2: 4; MSH6: 2; PMS2: 1), with 2 alleles (MLH1 c.677G > T and MSH2 с.1906G > C) detected twice. Testing for recurrent mutations of 30 consecutive MSI-H CRCs led to the identification of 2 additional subjects with LS. The analysis of all relevant publications identified 28 unrelated LS patients presented in Russian medical literature and 3 unrelated Russian LS subjects described in international journals. Overall, 15/49 (31%) genetic defects revealed in Russian LS patients were represented by six recurrent alleles (MLH1: c.350C > T, c.677G > T, c.1852_1854del; MSH2: c.942+3A > T, c.1861C > T, с.1906G > C). We conclude that the founder effect for LS in Russia is seemingly less pronounced than the one for hereditary breast-ovarian cancer syndrome, however testing for recurrent LS mutations may be considered feasible in some circumstances., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Exomes of 27 Russian subjects were analyzed for the presence of medically relevant alleles, such as protein-truncating variants (PTVs) in known recessive disease-associated genes and pathogenic missense mutations included in the ClinVar database. 36 variants (24 PTVs and 12 amino acid substitutions) were identified and then subjected to the analysis in 897 population controls. 9/36 mutations were novel, however only two of them (POLH c.490delG associated with xeroderma pigmentosum variant (XPV) and CATSPER1 c.859_860delCA responsible for spermatogenic failure) were shown to be recurrent. 27 out of 36 pathogenic alleles were already described in prior genetic studies; seven of them occurred only in the index cases, while 20 demonstrated evidence for persistence in Russian population. In particular, non-random occurrence was revealed for SERPINA1 c.1096G > A (alpha-1 antitrypsin deficiency), C8B c.1282C > T and c.1653G > A (complement component 8B deficiency), ATP7B c.3207C > A (Wilson disease), PROP1 c.301_302delAG (combined pituitary hormone deficiency), CYP21A2 c.844G > T (non-classical form of adrenogenital syndrome), EYS c.1155T > A (retinitis pigmentosa), HADHA c.1528G > C (LCHAD deficiency), SCO2 c.418G > A (cytochrome c oxidase deficiency), OTOA c.2359G > T (sensorineural deafness), C2 c.839_866del (complement component 2 deficiency), ACADVL c.848T > C (VLCAD deficiency), TGM5 c.337G > T (acral peeling skin syndrome) and VWF c.2561 G > A (von Willebrand disease, type 2N). These data deserve to be considered in future medical genetic activities., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Neoadjuvant therapy (NAT) is widely utilized in the routine management of cancer patients and various clinical trials for the treatment of breast, ovarian, rectal, esophageal, head and neck, lung, prostate and many other cancer types. There is a number of potential benefits of applying systemic treatment before the operation. NAT may significantly reduce the tumor burden thus allowing less traumatic surgery. NAT is often considered as personalized in vivo drug sensitivity test, as it allows rapid evaluation of tumor response to a given therapy and consequent adjustment of further treatment planning. NAT is an invaluable tool for in-human testing of novel therapeutic compounds, as it deals with yet chemonaive patients and permits pathological and molecular analysis of treatment-exposed tumor tissues. There are also some arguments against the use of NAT. The delay of surgery may increase the chances for metastatic tumor spread. NAT often results in the selection of treatment-resistant tumor clones, which cannot be eliminated by subsequent adjuvant therapy. NAT is likely to compromise visual inspection of surgical wound, as it reduces the size of tumor lumps and makes them invisible for the operating physician. Animal models cannot fully recapitulate the complexity of human cancer biology, the sophistication of modern surgical interventions, and the spectrum of tumor drug sensitivity in neoadjuvant and adjuvant settings. Therefore, studies on the rationale for NAT are largely limited to human studies.

In contrast to other countries with predominantly white populations, Russian smoking-related lung cancers (LC) are mainly squamous cell carcinomas and approximately half lung adenocarcinomas (AdCa) are not related to tobacco consumption. Given that smoking significantly influences the probability of presence of actionable mutations in LC, one would expect that Russian lung AdCa patients would differ from other white populations in distribution of EGFR, ALK, KRAS and BRAF mutations. Herein, 2,336 consecutive lung AdCa cases, including 1,203 patients with known smoking status, were subjected to sequential testing for the above mutations. One quarter of lung AdCa patients carried either EGFR or ALK mutation with combined prevalence of 42% in those who had never smoked but only 8% in smokers. There was only a moderate difference in KRAS mutation frequency between ever- and never-smokers in EGFR/ALK-negative cases (31% vs. 23%), and this was mainly attributed to increased prevalence of G12C substitution in the former group. The occurrence of BRAF V600E mutation was 1.7% and 4% in EGFR/ALK/KRAS mutation-negative ever- and never-smokers, respectively. ALK testing of 470 EGFR-mutated tumors revealed only 1 (0.2%) instance of translocation. Similarly, KRAS testing identified 1 (1.25%) mutation in 80 EGFR-mutated AdCa and none in 48 ALK-rearranged AdCa. Therefore, concurrent actionable mutations in lung adenocarcinoma are exceptionally rare and sequential gene testing can be regarded as a reliable option.

Background: Colorectal carcinomas (CRCs) are sensitive to treatment by anti-epidermal growth factor receptor (EGFR) antibodies only if they do not carry activating mutations in down-stream EGFR targets (KRAS/NRAS/BRAF). Most clinical trials for chemo-naive CRC patients involved combination of targeted agents and chemotherapy, while single-agent cetuximab or panitumumab studies included either heavily pretreated patients or subjects who were not selected on the basis of molecular tests. We hypothesized that anti-EGFR therapy would have significant efficacy in chemo-naive patients with KRAS/NRAS/BRAF mutation-negative CRC., Methods: Nineteen patients were prospectively included in the study., Results: Two (11%) patients experienced partial response (PR) and 11 (58%) subjects showed stable disease (SD). Median time to progression approached 6.1 months (range 1.6-15.0 months). Cetuximab efficacy did not correlate with RNA expression of EGFR and insulin-like growth factor 2 (IGF2). Only one tumor carried PIK3CA mutation, and this CRC responded to cetuximab. Exome analysis of patients with progressive disease (PD) revealed 1 CRC with high-level microsatellite instability and 1 instance of HER2 oncogene amplification; 3 of 4 remaining patients with PD had allergic reactions to cetuximab, while none of the subjects with PR or SD had this complication. Comparison with 19 retrospective KRAS/NRAS/BRAF mutation-negative patients receiving first-line fluoropyrimidines revealed no advantages or disadvantages of cetuximab therapy., Conclusions: Cetuximab demonstrates only modest efficacy when given as a first-line monotherapy to KRAS/NRAS/BRAF mutation-negative CRC patients. It is of question, why meticulous patient selection, which was undertaken in the current study, did not result in the improvement of outcomes of single-agent cetuximab treatment.

Distribution of cancer-predisposing mutations demonstrates significant interethnic variations. This study aimed to evaluate patterns of APC and MUTYH germ-line mutations in Russian patients with colorectal malignancies. APC gene defects were identified in 26/38 (68%) subjects with colon polyposis; 8/26 (31%) APC mutations were associated with 2 known mutational hotspots (p.E1309Dfs*4 [n = 5] and p.Q1062fs* [n = 3]), while 6/26 (23%) mutations were novel (p.K73Nfs*6, p.S254Hfs*12, p.S1072Kfs*9, p.E1547Kfs*11, p.L1564X and p.C1263Wfs*22). Biallelic mutations in MUTYH gene were detected in 3/12 (25%) remaining subjects with polyposis and in 6/90 (6.7%) patients with colorectal cancer (CRC) carrying KRAS p.G12C substitution, but not in 231 early-onset CRC cases negative for KRAS p.G12C allele. In addition to known European founder alleles p.Y179C and p.G396D, this study revealed a recurrent character of MUTYH p.R245H germ-line mutation. Besides that, 3 novel pathogenic MUTYH alleles (p.L111P, p.R245S and p.Q293X) were found. Targeted next-generation sequencing of 7 APC/MUTYH mutation-negative DNA samples identified novel potentially pathogenic POLD1 variant (p.L460R) in 1 patient and known low-penetrant cancer-associated allele CHEK2 p.I157T in 3 patients. The analysis of 1120 healthy subjects revealed 15 heterozygous carriers of recurrent MUTYH mutations, thus the expected incidence of MUTYH-associated polyposis in Russia is likely to be 1:23 000., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Tuberous sclerosis (TS) is a rare autosomal-dominant genetic disease. TS is manifested by the development of multiple hamartomas, which affect brain, kidneys, retina, skin and other organs. This study aimed to reveal specific features of molecular epidemiology of TS in Russia. Blood DNA samples from 61 patients with definite (n = 53) or probable (n = 8) clinical diagnosis of TS were tested for mutations in TSC1 and TSC2 genes using Sanger sequencing and MLPA analysis. Five TSC1/2 mutation-negative patients were further analyzed by exome sequencing. TSC1/2 mutations were detected in 53/61 patients (87%): 39 (74%) carried mutations in the TSC2 and 14 (26%) in the TSC1. Large rearrangements (exon deletions/duplications) affected exclusively TSC2, accounting for 15% of lesions of this gene. 6/8 (75%) patients with incomplete clinical manifestation of TS carried TSC1/2 gene lesion. Overall, 96% of detected germline TSC1/2 mutations occurred de novo. Patients with no mutation identified (NMI) differed from TSC1/2 mutation carriers, being lacking cortical tubers and subependymal nodules but having higher frequencies of renal angiomyolipomas, rhabdomyomas, and lymphangioleiomyomatosis. Exome sequencing failed to identify overt disease-causing mutation candidates among NMI patients. Russian patients with TS have increased frequency of TSC2 large gene rearrangements and TSC1/2 mutations occurring de novo as compared to other studies. Patients with suspected TS diagnosis but NMI status may represent a distinct disease entity.

Vemurafenib, a specific inhibitor of mutated BRAF kinase, may activate wild-type BRAF and therefore induce squamous cell skin carcinomas in patients treated for melanoma. All vemurafenib clinical trials excluded patients with multiple primary malignant tumors; therefore, the action of this drug on concurrent BRAF wild-type malignancies remains insufficiently studied. We observed a patient, who was administered vemurafenib for BRAF mutation-containing melanoma, but experienced immediate relapse of previously controlled breast cancer disease. Interestingly, breast cancer lesions underwent regression soon after vemurafenib discontinuation. Therefore, caution must be taken while considering vemurafenib treatment for patients with multiple tumors.

Preoperative therapy provides an advantage for clinical drug assessment, as it involves yet untreated patients and facilitates access to the post-treatment biological material. Testing for Slavic founder BRCA mutations was performed for 225 ovarian cancer (OC) patients, who were treated by platinum-based neoadjuvant therapy. 34 BRCA1 and 1 BRCA2 mutation carriers were identified. Complete clinical response was documented in 12/35 (34%) mutation carriers and 8/190 (4%) non-carriers (P = 0.000002). Histopathologic response was observed in 16/35 (46%) women with the germ-line mutation versus 42/169 (25%) patients with the wild-type genotype (P = 0.02). Somatic loss of heterozygosity (LOH) for the remaining wild-type BRCA1 allele was detected only in 7/24 (29%) post-neoadjuvant therapy residual tumor tissues as compared to 9/11 (82%) BRCA1-associated OC, which were not exposed to systemic treatment before the surgery (P = 0.009). Furthermore, comparison of pre- and post-treatment tumor material obtained from the same patients revealed restoration of BRCA1 heterozygosity in 2 out of 3 sample pairs presenting with LOH at diagnosis. The obtained data confirm high sensitivity of BRCA-driven OC to platinating agents and provide evidence for a rapid selection of tumor cell clones without LOH during the course of therapy., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

A nonsense mutation, p.Q548X, in the BLM gene has recently been associated with an increased risk for breast cancer. In the present work, we investigated the prevalence of this Slavic founder mutation in 2,561 ovarian cancer cases from Russia, Belarus, Poland, Lithuania or Germany and compared its frequency with 6,205 ethnically matched healthy female controls. The p.Q548X allele was present in nine ovarian cancer patients of Slavic ancestry (0.5 %; including one case with concurrent BRCA1 mutation). The mutation was not significantly more frequent in cases than in controls (Mantel-Haenszel OR 1.14, 95 % CI 0.49; 2.67). Ovarian tumours in p.Q548X carriers were mainly of the serous subtype, and there was little evidence for an early age at diagnosis or pronounced family history of cancer. These findings indicate that the BLM p.Q548X mutation is not a strong risk factor for ovarian cancer.

In a search for new breast cancer (BC) predisposing genes, we performed a whole exome sequencing analysis using six patient samples of familial BC and identified a germline inactivating mutation c.183delG [p. Arg61fs] in an orphan G protein-coupled receptor GPRC5A. An extended case-control study revealed a tenfold enrichment for this mutation in BC patients carrying the 5382insC allele of BRCA1, the major founder mutation in the Russian population, compared to wild-type BRCA1 BC cases [6/117 (5.1%) vs. 8/1578 (0.5%), p = 0.0002]. In mammary tumors (n = 60), the mRNA expression of GPRC5A significantly correlated with that of BRCA1 (p = 0.00018). In addition, the amount of GPRC5A transcript was significantly lower in BC obtained from BRCA1 mutation carriers (n = 17) compared to noncarriers (n = 93) (p = 0.026). Accordingly, a siRNA-mediated knockdown of either BRCA1 or GPRC5A in the MDA-MB-231 human BC cell line reduced expression of GPRC5A or BRCA1, respectively. Knockdown of GPRC5A also attenuated radiation-induced BRCA1- and RAD51-containing nuclear DNA repair foci. Taken together, these data suggest that GPRC5A is a modifier of BC risk in BRCA1 mutation carriers and reveals a functional interaction of these genes., (© 2013 UICC.)

Somatic inactivation of the remaining allele is a characteristic feature of cancers arising in BRCA1 and BRCA2 mutation carriers, which determines their unprecedented sensitivity to some DNA-damaging agents. Data on tumor-specific status of the involved gene in novel varieties of hereditary breast cancer (BC) remain incomplete. We analyzed 32 tumors obtained from 30 patients with non-BRCA1/2 BC-associated germ-line mutations: 25 women were single mutation carriers (7 BLM, 15 CHEK2 and 3 NBN/NBS1) and 5 were double mutation carriers (2 BLM/BRCA1, 1 CHEK2/BLM, 1 CHEK2/BRCA1 and 1 NBN/BLM). Losses of heterozygosity affecting the wild-type allele were detected in none of the tumors from BLM mutation carriers, 3/18 (17 %) CHEK2-associated BC and 1/4 (25 %) NBN/NBS1-driven tumors. The remaining 28 BC were subjected to the sequence analysis of entire coding region of the involved gene; no somatic mutations were identified. We conclude that the tumor-specific loss of the wild-type allele is not characteristic for BC arising in CHEK2, NBN/NBS1 and BLM mutation carriers. Rarity of "second-hit" inactivation of the involved gene in CHEK2-, NBN/NBS1- and BLM-associated BC demonstrates their substantial biological difference from BRCA1/2-driven cancers and makes them poorly suitable for the clinical trials with cisplatin and PARP inhibitors.

Sensitivity of gastric cancer (GC) to conventional cytotoxic therapy may be at least in part attributed to molecular features of the tumor cells. We analyzed all patients with metastatic GC treated in the N.N. Petrov Institute of Oncology (St. Petersburg) within years 1999-2010 and identified 65 cases with evaluable treatment response and available biological material. Two of 65 patients (3 %) carried germ-line BRCA1 5382insC mutation and demonstrated particularly pronounced response to the treatment; both of their tumors showed loss of the remaining BRCA1 allele, thus confirming the causative role of BRCA1 heterozygosity in GC predisposition. RNA expression of TS, DPD, BRCA1, ERCC, TOP2A and bTUBIII was analyzed in the remaining 63 tumors. Low BRCA1 expression was associated with increased response rate [6/9 (67 %) vs. 17/54 (32 %), p = 0.04]. Low bTUBIII level correlated with the improved probability of tumor response [21/49 (43 %) vs. 1/13 (8 %), p = 0.02] and prolonged overall survival (10.5 vs. 7.1 months, p = 0.02); this trend was maintained both for taxane-containing and for taxane-free drug combinations. We conclude that GC should be considered as a part of BRCA1-related hereditary cancer syndrome. Tumors with BRCA1 inactivation and low bTUBIII expression demonstrate improved response to cytotoxic therapy.

Virtually all known tumor predisposing genes have been identified via the analysis of familial cancer cases. Here we argue that this approach is likely to miss recessively acting cancer genes and suggest the analysis of family history-negative patients with multiple primary malignancies for identifying homozygous at-risk genotypes. We performed calculations showing that the homozygous carriers of rare recessive cancer predisposing alleles are unlikely to report a family history of the disease. We further revealed that the c.2515_2519delAAGTT homozygous mutation in a Holliday junction resolvase, GEN1, was overrepresented in women with bilateral breast cancer (BC) as compared to healthy controls [11/360 (3.1 %) vs. 18/1305 (1.4 %); odds ratio (OR) = 2.25 (1.02-4.75); p = 0.031], although this trend was not maintained in unilateral BC patients [23/1851 (1.2 %)]. Noticeably, presence of biallelic c.2515_2519delAAGTT mutation was associated with the absence of BC in mother both in bilateral and unilateral BC cases [7/239 (3.0 %) vs. 0/41 (0 %) and 21/1,558 (1.3 %) vs. 0/215 (0 %), respectively; Mantel-Haenszel p = 0.041]. Thus, this study suggests that identification of dominant and recessive cancer predisposing genes may require distinct study groups.

Angiogenesis plays an important role in cancer progression and involves activation of multiple signaling cascades. This study investigated the relationships between microvessel density, expression of VEGF and VEGFR1 (FLT1), and gastric cancer (GC) recurrence. Twenty-nine surgically treated GC cases with similar initial clinical presentation were selected for the study; 11 of these cases recurred within 3 years, while the remaining 18 did not. Microvessel density correlated with VEGF mRNA content, but neither of these parameters was associated with the disease outcome. When tumors were ranked according to the level of expression of angiogenic molecules, 9 out of 10 cases with the highest VEGFR1 expression belonged to the recurrence group, while none of the 10 GC with the lowest content of VEGFR1 mRNA had the disease relapse (p = 0.000). VEGFR1 expression did not show even a trend to correlation with the level of cancer tissue vascularization. Immunofluorescent staining by anti-VEGFR1 antibody revealed VEGFR1 expression in tumor cells but not in other cell types. Our data provide indirect support to the evidence for a non-angiogenic contribution of VEGFR1 in cancer pathogenesis.

One hundred and ninety-five consecutive surgically treated Russian colorectal cancer (CRC) patients were retrospectively analyzed for the presence of mutations in KRAS, NRAS, BRAF and PIK3CA genes as well as for the microsatellite instability status. Comparison between high-resolution melting analysis, co-amplification at lower denaturation temperature PCR, DNA sequencing and allele-specific PCR for the detection of KRAS codon 12/13 mutations revealed that none of these methods alone provided satisfactory results in 100 % of the analyzed cases; this experience supports the use of more than one mutation-detecting technique at least in some circumstances. KRAS codon 12/13 substitutions were detected in 70 (35.9 %) CRC cases. Other mutations in the RAS/RAF genes occurred in 22 (11.3 %) cases and included rare KRAS (n = 6), NRAS (n = 8) and BRAF (n = 8) alterations. 5 BRAF mutations affected codon 600, while the remaining 3 potentially functional substitutions were located in the position 594. Twenty-four (12.3 %) CRC cases carried mutations in the PIK3CA, and 18 of these tumors also contained activating alteration in the RAS/RAF genes (p = 0.007). Only 3 (1.5 %) CRC cases showed high-level microsatellite instability (MSI-H) as determined by a panel of mononucleotide markers. Overall, the distribution of potentially predictive mutations in Russian CRC cases is similar to the one observed in other patient series of European descent. Noticeable occurrence of D594G mutation in BRAF oncogene and low frequency of MSI-H may deserve specific attention.

Hereditary breast-ovarian cancer syndrome contributes to as much as 5-7% of breast cancer (BC) and 10-15% of ovarian cancer (OC) incidence. Mutations in the "canonical" genesBRCA1andBRCA2occur in 20-30% of affected pedigrees. In addition toBRCA1andBRCA2 mutations, germ-line lesions in theCHEK2,NBS1, andPALB2genes also contribute to familial BC clustering. The epidemiology of hereditary breast-ovarian cancer in Russia has some specific features. The impact of the "founder" effect is surprisingly remarkable: a single mutation,BRCA15382insC, accounts for the vast majority ofBRCA1defects across the country. In addition, there are two other recurrentBRCA1alleles:BRCA14153delA andBRCA1185delAG. BesidesBRCA1, in Russia breast cancer is often caused by germ-line alterations in theCHEK2andNBS1genes. In contrast toBRCA1andBRCA2, theCHEK2andNBS1heterozygosity does not significantly increase the OC risk. Several Russian breast cancer clinics recently started to investigate the efficacy of cisplatin in the therapy ofBRCA1-related cancers; initial results show a unique sensitivity ofBRCA1-associated tumours to this compound.

Our previous studies, which included genotyping of multiple coding apoptotic gene polymorphisms, unexpectedly demonstrated a depletion of heterozygous CASP5 Ala90Thr (rs507879, c.268 G>A) genotypes in elderly subjects. Present investigation was aimed to validate this trend. An analysis of 510 subjects aged 75-103years revealed 205 (40%) CASP5 Ala90Thr heterozygotes as compared to 254 (50%) expected from the minor allele frequency 0.470 (p=0.000014). This deviation was not observed in 549 middle-aged (18-50years) controls (270 (49%) heterozygotes observed vs. 274 (50%) expected; minor allele frequency 0.475; p=0.743). Unfavorable significance of CASP5 heterozygous genotype may be explained by the role of the caspase-5 in inflammation-related processes. Almost all prior gene-longevity association studies focused on discrimination between "good" and "bad" gene variants. Here we present a distinct situation, where the combination of alternative alleles (i.e., heterozygosity) appears to be unfavorable as compared to the homozygous carriership of either gene variant., (Copyright 2010 Elsevier Inc. All rights reserved.)