Background & Aims Multigene panels are commercially available tools for hereditary cancer risk assessment that allow for next-generation sequencing of numerous genes in parallel. However, it is not clear if these panels offer advantages over traditional genetic testing. We investigated the number of cancer predisposition gene mutations identified by parallel sequencing in individuals with suspected Lynch syndrome. Methods We performed germline analysis with a 25-gene next-generation sequencing panel using DNA from 1260 individuals who underwent clinical genetic testing for Lynch syndrome from 2012 through 2013. All subjects had a history of Lynch syndrome-associated cancer and/or polyps. We classified all identified germline alterations for pathogenicity and calculated the frequencies of pathogenic mutations and variants of uncertain significance (VUS). We also analyzed data on patients’ personal and family history of cancer, including fulfillment of clinical guidelines for genetic testing. Results Of the 1260 subjects, 1112 met National Comprehensive Cancer Network (NCCN) criteria for Lynch syndrome testing (88%; 95% confidence interval [CI], 86%–90%). Multigene panel testing identified 114 probands with Lynch syndrome mutations (9.0%; 95% CI, 7.6%−10.8%) and 71 with mutations in other cancer predisposition genes (5.6%; 95% CI, 4.4%−7.1%). Fifteen individuals had mutations in BRCA1 or BRCA2; 93% of these met the NCCN criteria for Lynch syndrome testing and 33% met NCCN criteria for BRCA1 and BRCA2 analysis (P=.0017). An additional 9 individuals carried mutations in other genes linked to high lifetime risks of cancer (5 had mutations in APC, 3 had bi-allelic mutations in MUTYH, and 1 had a mutation in STK11); all of these patients met NCCN criteria for Lynch syndrome testing. Four hundred seventy-nine individuals had ≥1 VUS (38%; 95% CI, 35%–41%). Conclusions In individuals with suspected Lynch syndrome, multigene panel testing identified high-penetrance mutations in cancer predisposition genes, many of which were unexpected based on patients’ histories. Parallel sequencing also detected a high number of potentially uninformative germline findings, including VUS.

BACKGROUND: Current estimates of the contribution of large rearrangement (LR) mutations in the BRCA1 (breast cancer 1, early onset) and BRCA2 (breast cancer 2, early onset) genes responsible for hereditary breast and ovarian cancer are based on limited studies of relatively homogeneous patient populations. The prevalence of BRCA1/2 LRs was investigated in 48,456 patients with diverse clinical histories and ancestries, referred for clinical molecular testing for suspicion of hereditary breast and ovarian cancer. METHODS: Sanger sequencing analysis was performed for BRCA1/2 and LR testing for deletions and duplications using a quantitative multiplex polymerase chain reaction assay. Prevalence data were analyzed for patients from different risk and ethnic groups between July 2007 and April 2011. Patients were designated as “high-risk” if their clinical history predicted a high prior probability, wherein LR testing was performed automatically in conjunction with sequencing. “Elective” patients did not meet the high-risk criteria, but underwent LR testing as ordered by the referring health care provider. RESULTS: Overall BRCA1/2 mutation prevalence among high-risk patients was 23.8% versus 8.2% for the elective group. The mutation profile for high-risk patients was 90.1% sequencing mutations versus 9.9% LRs, and for elective patients, 94.1% sequencing versus 5.9% LRs. This difference may reflect the bias in high-risk patients to carry mutations in BRCA1, which has a higher penetrance and frequency of LRs compared with BRCA2. There were significant differences in the prevalence and types of LRs in patients of different ancestries. LR mutations were significantly more common in Latin American/Caribbean patients. CONCLUSIONS: Comprehensive LR testing in conjunction with full gene sequencing is an appropriate strategy for clinical BRCA1/2 analysis.

Background: Large rearrangements account for 8% to 15% of deleterious BRCA mutations, although none have been characterized previously in individuals of Mexican ancestry. Methods: DNA from 106 Hispanic patients without an identifiable BRCA mutation by exonic sequence analysis was subjected to multiplexed quantitative differential PCR. One case of Native American and African American ancestry was identified via multiplex ligation-dependent probe amplification. Long-range PCR was used to confirm deletion events and to clone and sequence genomic breakpoints. Splicing patterns were derived by sequencing cDNA from reverse transcription-PCR of lymphoblastoid cell line RNA. Haplotype analysis was conducted for recurrent mutations. Results: The same deletion of BRCA1 exons 9 through 12 was identified in five unrelated families. Long-range PCR and

BackgroundGermline DNA mutations that increase the susceptibility of a patient to certain cancers have been identified in various genes, and patients can be screened for mutations in these genes to assess their level of risk for developing cancer. Traditional methods using Sanger sequencing focus on small groups of genes and therefore are unable to screen for numerous genes from several patients simultaneously. The goal of the present study was to validate a 25-gene panel to assess genetic risk for cancer in 8 different tissues using next generation sequencing (NGS) techniques.MethodsTwenty-five genes associated with hereditary cancer syndromes were selected for development of a panel to screen for risk of these cancers using NGS. In an initial technical assessment, NGS results for BRCA1 and BRCA2 were compared with Sanger sequencing in 1864 anonymized DNA samples from patients who had undergone previous clinical testing. Next, the entire gene panel was validated using parallel NGS and Sanger sequencing in 100 anonymized DNA samples. Large rearrangement analysis was validated using NGS, microarray comparative genomic hybridization (CGH), and multiplex ligation-dependent probe amplification analyses (MLPA).ResultsNGS identified 15,877 sequence variants, while Sanger sequencing identified 15,878 in the BRCA1 and BRCA2 comparison study of the same regions. Based on these results, the NGS process was refined prior to the validation of the full gene panel. In the validation study, NGS and Sanger sequencing were 100% concordant for the 3,923 collective variants across all genes for an analytical sensitivity of the NGS assay of >99.92% (lower limit of 95% confidence interval). NGS, microarray CGH and MLPA correctly identified all expected positive and negative large rearrangement results for the 25-gene panel.ConclusionThis study provides a thorough validation of the 25-gene NGS panel and indicates that this analysis tool can be used to collect clinically significant information related to risk of developing hereditary cancers.

This work describes an approach to characterize the clinical significance of genetic variants detected during the genetic testing of BRCA1 in patients from hereditary breast/ovarian cancer families. Results from transgenic mice and extensive clinical testing support the hypothesis that biallelic BRCA1 mutations result in embryonic lethality. Therefore, it is reasonable to conclude that variants of uncertain clinical significance found to reside in trans with known deleterious mutations impart reduced risk for cancer. This approach was applied to a large data set of 55,630 patients who underwent clinical BRCA1 screening by whole gene direct DNA sequencing. Fourteen common single nucleotide polymorphisms (SNPs) were used to assign 10 previously defined common, recurrent, or canonical haplotypes in 99% of these cases. From a total of 1,477 genetic variants detected in these patients, excluding haplotype-tagging SNPs, 877 (59%) could be unambiguously assigned to one or more haplotypes. In 41 instances, variants previously classified as being of uncertain clinical significance, mostly missense variants, were excluded as fully penetrant mutations due to their coincidence in trans with known deleterious mutations. From a total of 1,150 patients that harbored these 41 variants, 956 carried one as the sole variant of uncertain clinical significance reported. This approach could have widespread application to other disease genes where compound heterozygous mutations are incompatible with life or result in obvious phenotypes. This largely computational technique is advantageous because it relies upon existing clinical data and is likely to prove informative for prevalent genetic variants in large data sets.

PURPOSE Women with a family history of breast cancer are frequently referred for hereditary cancer genetic testing, yet < 10% are found to have pathogenic variants in known breast cancer susceptibility genes. Large-scale genotyping studies have identified common variants (primarily single-nucleotide polymorphisms [SNPs]) with individually modest breast cancer risk that, in aggregate, account for considerable breast cancer susceptibility. Here, we describe the development and empirical validation of an SNP-based polygenic breast cancer risk score. METHODS A panel of 94 SNPs was examined for association with breast cancer in women of European ancestry undergoing hereditary cancer genetic testing and negative for pathogenic variants in breast cancer susceptibility genes. Candidate polygenic risk scores (PRSs) as predictors of personal breast cancer history were developed through multivariable logistic regression models adjusted for age, cancer history, and ancestry. An optimized PRS was validated in 2 independent cohorts (n = 13,174; n = 141,160). RESULTS Within the training cohort (n = 24,259), 4,291 women (18%) had a personal history of breast cancer and 8,725 women (36%) reported breast cancer in a first-degree relative. The optimized PRS included 86 variants and was highly predictive of breast cancer status in both validation cohorts ( P = 6.4 × 10−66; P < 10−325). The odds ratio (OR) per unit standard deviation was consistent between validations (OR, 1.45 [95% CI, 1.39 to 1.52]; OR 1.47 [95% CI, 1.45 to 1.49]). In a direct comparison, the 86-SNP PRS outperformed a previously described PRS of 77 SNPs. CONCLUSION The validation and implementation of a PRS for women without pathogenic variants in known breast cancer susceptibility genes offers potential for risk stratification to guide surveillance recommendations.

Cancer risks have been previously reported for some retrotransposon element (RE) insertions; however, detection of these insertions is technically challenging and very few oncogenic RE insertions have been reported. Here we evaluate RE insertions identified during hereditary cancer genetic testing using a comprehensive testing strategy. Individuals who had single-syndrome or pan-cancer hereditary cancer genetic testing from February 2004 to March 2017 were included. RE insertions were identified using Sanger sequencing, Next Generation Sequencing, or multiplex quantitative PCR, and further characterized using targeted PCR and sequencing analysis. Personal cancer history, ancestry, and haplotype were evaluated. A total of 37 unique RE insertions were identified in 10 genes, affecting 211 individuals. BRCA2 accounted for 45.9% (17/37) of all unique RE insertions. Several RE insertions were detected with high frequency in populations of conserved ancestry wherein up to 100% of carriers shared a high degree of haplotype conservation, suggesting founder effects. Our comprehensive testing strategy resulted in a substantial increase in the number of reported oncogenic RE insertions, several of which may have possible founder effects. Collectively, these data show that the detection of RE insertions is an important component of hereditary cancer genetic testing and may be more prevalent than previously reported.

M utations in the base excision repair gene MYH were recently implicated in recessive inheritance of colorectal adenomas and carcinomas. 1 The majority of patient specimens screened for MYH and described in published reports derive from the United Kingdom, where two missense variants-Y165C and G382D-are the most prevalent mutations in the white population. [2][3][4][5] The carrier frequency for these two mutations is approximately 2% in the British population. Some additional mutations were detected at lower frequency in these patients. Two other protein truncating mutations-E466X and Y90X-have been found in individuals of Indian and Pakistani descent, respectively.2 3 Finally, a mutation that deletes codon Glu-466 was reported to be prevalent in Italian patients. 6 This evidence supports the view that additional mutations will be discovered showing differences in prevalence between ancestries.We determined the mutation spectrum for MYH by direct DNA sequencing in 219 anonymous North American patient specimens found negative for APC mutations during clinical genetic testing for risk assessment for familial adenomatous polyposis (FAP). All specimens were first sequenced for exons 7 and 13, where 13 instances (5.9%) of biallelic mutations and 15 instances (6.8%) of heterozygous mutations of either Y165C or G382D were detected (table 1).The remaining 202 specimens with one or no mutations and with sufficient DNA were sequenced at MYH for all exons and intron-exon boundaries. Sequencing identified a second mutation in nine of the 15 heterozygous carriers of Y165C and G382D. Two of these mutations-891+3A.C and 1103delC-have been described previously, 3 4 while others (E182X, Q300X and IVS13+25del30) are novel. IVS13+25del30 was considered a mutation because it deletes 30 bases from an 85 base intron and therefore seems likely to interfere with RNA splicing. Also, one homozygous patient each for two previously reported mutations-E466X and 1395delGGA-were detected. Small deletions affecting exons within the MYH locus were excluded as potential causes for an apparent homozygous result in these patients by long range polymerase chain reaction extending from exons 1 to 16. A North American population frequency of 2% was determined by identifying three Y165C and seven G382D heterozygous carriers when 497 anonymous samples that were negative for clinical factor V Leiden tests were screened at exons 7 and 13. This carrier frequency is similar to that reported in two European studies. MYH mutations were also assessed in 306 anonymous North American specimens found negative for clinical testing in hMLH1 and hMSH2 as part of an analysis of risk for hereditary non-polyposis colorectal cancer (HNPCC). All 306 specimens were initially screened for Y165C and G382D; three specimens (1.0%) carried biallelic mutations and 10 specimens (3.3%) were heterozygotes. One instance of the 891+3ARC mutation was found when the entire MYH gene was sequenced in these 10 heterozygous specimens. When an additional 50 of the HNPCC negative specimens...