Clinician-Reported Management Recommendations in Response to Universal Germline Genetic Testing in Patients With Prostate Cancer.

PURPOSE: Identification of pathogenic germline variants in patients with prostate cancer can help inform treatment selection, screening for secondary malignancies, and cascade testing. Limited real-world data are available on clinician recommendations following germline genetic testing in patients with prostate cancer. MATERIALS AND METHODS: Patient data and clinician recommendations were collected from unselected patients with prostate cancer who underwent germline testing through the PROCLAIM trial. Differences among groups of patients were determined by 2-tailed Fisher's exact test with significance set at P < .05. Logistic regression was performed to assess the influence of test results in clinical decision-making while controlling for time of diagnosis (newly vs previously diagnosed). RESULTS: Among 982 patients, 100 (10%) were positive (>1 pathogenic germline variant), 482 (49%) had uncertain results (>1 variant of uncertain significance), and 400 (41%) were negative. Patients with positive results were significantly more likely than those with negative or uncertain results to receive recommendations for treatment changes (18% vs 1.4%, P < .001), follow-up changes (64% vs 11%, P < .001), and cascade testing (71% vs 5.4%, P < .001). Logistic regression demonstrated that positive and uncertain results were significantly associated with both changes to treatment and follow-up (P < .001) when controlling for new or previous diagnosis. CONCLUSIONS: Germline genetic testing results informed clinical recommendations for patients with prostate cancer, especially in patients with positive results. Higher than anticipated rates of clinical management changes in patients with uncertain results highlight the need for increased genetic education of clinicians treating patients with prostate cancer.

Diagnostic and clinical utility of comprehensive multigene panel testing for patients with neuropathy.

BACKGROUND AND AIMS: Prior to next-generation sequencing (NGS), the evaluation of a patient with neuropathy typically consisted of screening for acquired causes, followed by clinical genetic testing of PMP22, MFN2, GJB1, and MPZ in patients with a positive family history and symptom onset prior to age 50. In this study, we examined the clinical utility of NGS in a large cohort of patients analyzed in a commercial laboratory. METHODS: A cohort of 6849 adult patients underwent clinician-ordered peripheral neuropathy multigene panel testing ranging from 66 to 111 genes that included NGS and intragenic deletion/duplication analysis. RESULTS: A molecular diagnosis was identified for 8.4% of the cohort (n = 573/6849). Variants in PMP22, MFN2, GJB1, MPZ, and TTR accounted for 73.8% of molecular diagnoses. Results had potential clinical actionability for 398 (69.5%) patients. Our results suggest that 225/573 (39.3%) of molecular diagnoses and 113/398 (28.4%) of clinical interventions would have been missed if the testing approach had been restricted to older guidelines. INTERPRETATION: Our results highlight the need for expanded genetic testing guidelines that account for the increased number of genes associated with hereditary neuropathy, address the overlap of acquired and hereditary neuropathy, and provide broader access to genetic diagnosis for patients.

The landscape of reported VUS in multi-gene panel and genomic testing: Time for a change.

PURPOSE: Variants of uncertain significance (VUS) are a common result of diagnostic genetic testing and can be difficult to manage with potential misinterpretation and downstream costs, including time investment by clinicians. We investigated the rate of VUS reported on diagnostic testing via multi-gene panels (MGPs) and exome and genome sequencing (ES/GS) to measure the magnitude of uncertain results and explore ways to reduce their potentially detrimental impact. METHODS: Rates of inconclusive results due to VUS were collected from over 1.5 million sequencing test results from 19 clinical laboratories in North America from 2020 to 2021. RESULTS: We found a lower rate of inconclusive test results due to VUSs from ES/GS (22.5%) compared with MGPs (32.6%; P < .0001). For MGPs, the rate of inconclusive results correlated with panel size. The use of trios reduced inconclusive rates (18.9% vs 27.6%; P < .0001), whereas the use of GS compared with ES had no impact (22.2% vs 22.6%; P = ns). CONCLUSION: The high rate of VUS observed in diagnostic MGP testing warrants examining current variant reporting practices. We propose several approaches to reduce reported VUS rates, while directing clinician resources toward important VUS follow-up.

Racial disparities in cascade testing for cancer predisposition genes.

We sought to determine whether there are racial disparities in cascade testing rates and whether providing testing at no-charge impacts rates in Black and White at-risk-relatives (ARR). Probands with a pathogenic/likely pathogenic germline variant in a cancer predisposition gene were identified up to one year before and up to one year after cascade testing became no-charge in 2017. Cascade testing rates were measured as the proportion of probands who had at least one ARR obtain genetic testing through one commercial laboratory. Rates were compared between self-reported Black and White probands using logistic regression. Interaction between race and cost (pre/post policy) was tested. Significantly fewer Black probands than White probands had at least one ARR undergo cascade genetic testing (11.9% versus 21.7%, OR 0.49, 95% CI 0.39-0.61, p < 0.0001). This was seen both before (OR 0.38, 95% CI 0.24-0.61, p < 0.001) and after (OR 0.53, 95% CI 0.41-0.68, p < 0.001) the no-charge testing policy. Rates of an ARR undergoing cascade testing were low overall, and significantly lower in Black versus White probands. The magnitude of difference in cascade testing rates between Blacks and Whites did not significantly change with no-charge testing. Barriers to cascade testing in all populations should be explored in order to maximize the benefits of genetic testing for both treatment and prevention of cancer.

Fumarate hydratase variant prevalence and manifestations among individuals receiving germline testing.

BACKGROUND: Germline variants in fumarate hydratase (FH) are associated with autosomal dominant (AD) hereditary leiomyomatosis and renal cell cancer (HLRCC) and autosomal recessive (AR) fumarase deficiency (FMRD). The prevalence and cancer penetrance across different FH variants remain unclear. METHODS: A database containing 120,061 records from individuals undergoing cancer germline testing was obtained. FH variants were classified into 3 categories: AD HLRCC variants, AR FMRD variants, and variants of unknown significance (VUSs). Individuals with variants from these categories were compared with those with negative genetic testing. RESULTS: FH variants were detected in 1.3% of individuals (AD HLRCC, 0.3%; AR FMRD, 0.4%; VUS, 0.6%). The rate of AD HLRCC variants discovered among reportedly asymptomatic individuals without a clear indication for HLRCC testing was 1 in 2668 (0.04%). In comparison with those with negative genetic testing, the renal cell carcinoma (RCC) prevalence was elevated with AD HLRCC variants (17.0% vs 4.5%; P < .01) and VUSs (6.4% vs 4.5%; P = .02) but not with AR FMRD variants. CONCLUSIONS: The prevalence of HLRCC discovered incidentally on germline testing is similar to recent population carrier estimates, and this suggests that this is a relatively common cancer syndrome. Compared with those with negative genetic testing, those with VUSs had an elevated risk of RCC, whereas those with AR FMRD variants did not.

Cancer risks associated with heterozygous ATM loss of function and missense pathogenic variants based on multigene panel analysis.

PURPOSE: Cancer risks conferred by germline, heterozygous, ATM pathogenic/likely pathogenic variants (PSVs) are yet to be consistently determined. The current study assessed these risks by analysis of a large dataset of ATM heterozygote loss of function (LOF) and missense PSV carriers tested with a multigene panel (MGP). METHODS: De-identified data of all individuals who underwent ATM sequencing as part of MGP between October 2015 and February 2020 were reviewed. In cancer cases, rates for the six most prevalent variants and for all LOF and missense PSV combined were compared with rates of the same PSV in ethnically matched, healthy population controls. Statistical analysis included Chi-square tests and odds ratios calculations. RESULTS: For female breast cancer cases, LOF )1794/219,269) and missense (301/219,269) ATM PSVs were seen at higher rates compared to gnomAD non-cancer controls (n = 157/56,001 and n = 27/61,208; p < 0.00001, respectively). Notably, the rate of the c.103C > T variant was higher in controls than in breast cancer cases [p = 0.001; OR 0.31 (95% CI 0.1-0.6)]. For all cancer cases combined, compared with non-cancer population controls, LOF (n = 143) and missense (n = 15) PSVs reported in both datasets were significantly more prevalent in cancer cases [ORLOF 1.7 (95% 1.5-1.9) ORmissense 3.0 (95% CI 2.3-4); p = 0.0001]. CONCLUSION: Both LOF and missense heterozygous ATM PSVs are more frequently detected in cases of several cancer types (breast, ovarian, prostate, lung, pancreatic) compared with healthy population controls. However, not all ATM PSVs confer an increased cancer risk (e.g., breast).

Multi-ethnic analysis shows genetic risk and environmental predictors interact to influence 25(OH)D concentration and optimal vitamin D intake.

25-Hydroxyvitamin D (25(OH)D) concentration is a complex trait with genetic and environmental predictors that may determine how much vitamin D exposure is required to reach optimal concentration. Interactions between continuous measures of a polygenic score (PGS) and vitamin D intake (PGS*intake) or available ultraviolet (UV) radiation (PGS*UV) were evaluated in individuals of African (n = 1,099) or European (n = 8,569) ancestries. Interaction terms and joint effects (main and interaction terms) were tested using one-degree of freedom (1-DF) and 2-DF models, respectively. Models controlled for age, sex, body mass index, cohort, and dietary intake/available UV. In addition, in participants achieving Institute of Medicine (IOM) vitamin D intake recommendations, 25(OH)D was evaluated by level PGS. The 2-DF PGS*intake, 1-DF PGS*UV, and 2-DF PGS*UV results were statistically significant in participants of European ancestry (p = 3.3 × 10-18 , p = 2.1 × 10-2 , and p = 2.4 × 10-19 , respectively), but not in those of African ancestry. In European-ancestry participants reaching IOM vitamin D intake guidelines, the percent of participants achieving adequate 25(OH)D ( >20 ng/ml) increased as genetic risk decreased (72% vs. 89% in highest vs. lowest risk; p = .018). Available UV radiation and vitamin D intake interact with genetics to influence 25(OH)D. Individuals with higher genetic risk may require more vitamin D exposure to maintain optimal 25(OH)D concentrations.

Physician-directed genetic screening to evaluate personal risk for medically actionable disorders: a large multi-center cohort study.

BACKGROUND: The use of proactive genetic screening for disease prevention and early detection is not yet widespread. Professional practice guidelines from the American College of Medical Genetics and Genomics (ACMG) have encouraged reporting pathogenic variants that confer personal risk for actionable monogenic hereditary disorders, but only as secondary findings from exome or genome sequencing. The Centers for Disease Control and Prevention (CDC) recognizes the potential public health impact of three Tier 1 actionable disorders. Here, we report results of a large multi-center cohort study to determine the yield and potential value of screening healthy individuals for variants associated with a broad range of actionable monogenic disorders, outside the context of secondary findings. METHODS: Eligible adults were offered a proactive genetic screening test by health care providers in a variety of clinical settings. The screening panel based on next-generation sequencing contained up to 147 genes associated with monogenic disorders within cancer, cardiovascular, and other important clinical areas. Sequence and intragenic copy number variants classified as pathogenic, likely pathogenic, pathogenic (low penetrance), or increased risk allele were considered clinically significant and reported. Results were analyzed by clinical area and severity/burden of disease using chi-square tests without Yates' correction. RESULTS: Among 10,478 unrelated adults screened, 1619 (15.5%) had results indicating personal risk for an actionable monogenic disorder. In contrast, only 3.1 to 5.2% had clinically reportable variants in genes suggested by the ACMG version 2 secondary findings list to be examined during exome or genome sequencing, and 2% had reportable variants related to CDC Tier 1 conditions. Among patients, 649 (6.2%) were positive for a genotype associated with a disease of high severity/burden, including hereditary cancer syndromes, cardiovascular disorders, or malignant hyperthermia susceptibility. CONCLUSIONS: This is one of the first real-world examples of specialists and primary care providers using genetic screening with a multi-gene panel to identify health risks in their patients. Nearly one in six individuals screened for variants associated with actionable monogenic disorders had clinically significant results. These findings provide a foundation for further studies to assess the role of genetic screening as part of regular medical care.

Ancestry-specific polygenic scores and SNP heritability of 25(OH)D in African- and European-ancestry populations.

Vitamin D inadequacy, assessed by 25-hydroxyvitamin D [25(OH)D], affects around 50% of adults in the United States and is associated with numerous adverse health outcomes. Blood 25(OH)D concentrations are influenced by genetic factors that may determine how much vitamin D intake is required to reach optimal 25(OH)D. Despite large genome-wide association studies (GWASs), only a small portion of the genetic factors contributing to differences in 25(OH)D has been discovered. Therefore, knowledge of a fuller set of genetic factors could be useful for risk prediction of 25(OH)D inadequacy, personalized vitamin D supplementation, and prevention of downstream morbidity and mortality. Using PRSice and weights from published African- and European-ancestry GWAS summary statistics, ancestry-specific polygenic scores (PGSs) were created to capture a more complete set of genetic factors in those of European (n = 9569) or African ancestry (n = 2761) from three cohort studies. The PGS for African ancestry was derived using all input SNPs (a p value cutoff of 1.0) and had an R2 of 0.3%; for European ancestry, the optimal PGS used a p value cutoff of 3.5 × 10-4 in the target/tuning dataset and had an R2 of 1.0% in the validation cohort. Those with highest genetic risk had 25(OH)D that was 2.8-3.0 ng/mL lower than those with lowest genetic risk (p = 0.0463-3.2 × 10-13), requiring an additional 467-500 IU of vitamin D intake to maintain equivalent 25(OH)D. PGSs are a powerful predictive tool that could be leveraged for personalized vitamin D supplementation to prevent the negative downstream effects of 25(OH)D inadequacy.

Early genetic testing in pediatric epilepsy: Diagnostic and cost implications.

The identification of numerous genetically based epilepsies has resulted in the widespread use of genetic testing to inform epilepsy etiology. Our study aims to investigate whether a difference exists in the diagnostic evaluation and healthcare-related cost expenditures of pediatric patients with epilepsy of unknown etiology who receive a genetic diagnosis through multigene epilepsy panel (MEP) testing and comparing those who underwent early (EGT) versus late genetic testing (LGT). Testing was defined as early (less than 1 year), or late (more than 1 year), following clinical epilepsy diagnosis. A retrospective chart review of pediatric individuals (1-17 years) with epilepsy of unknown etiology who underwent multigene epilepsy panel (MEP) testing identified 28 of 226 (12%) individuals with a pathogenic epilepsy variant [EGT n = 8 (29%); LGT n = 20 (71%)]. The average time from clinical epilepsy diagnosis to genetic diagnosis was 0.25 years (EGT), compared with 7.1 years (LGT). The EGT cohort underwent fewer metabolic tests [EGT n = 0 (0%); LGT n = 16 (80%) (P < 0.01)] and invasive procedures [EGT n = 0 (0%); LGT n = 5 (25%) (P = 0.06)]. Clinical management changes implemented due to genetic diagnosis occurred in 10 (36%) patients [EGT n = 2 (25%); LGT n = 8 (40%) (P = 0.76)]. Early genetic testing with a MEP in pediatric patients with epilepsy of unknown etiology who receive a genetic diagnosis is associated with fewer non-diagnostic tests and invasive procedures and reduced estimated overall healthcare-related costs. PLAIN LANGUAGE SUMMARY: This study aims to investigate whether a difference exists in the diagnostic evaluation and cost expenditures of pediatric patients (1-17 years) with epilepsy of unknown cause who are ultimately diagnosed with a genetic cause of epilepsy through multigene epilepsy panel testing and comparing those who underwent early testing (less than 1 year) versus late testing (more than 1 year) after clinical epilepsy diagnosis. Of the 28 of 226 individuals with a confirmed genetic cause of epilepsy on multigene epilepsy panel testing, performing early testing was associated with fewer non-diagnostic tests, fewer invasive procedures and reduced estimated overall healthcare-related costs.

Fumarate Hydratase Variants and Their Association With Paraganglioma/Pheochromocytoma.

OBJECTIVE: To clarify the link between germline variants in fumarate hydratase (FH), hereditary leiomyomatosis and renal cell cancer (HLRCC), and paraganglioma (PGL) and pheochromocytoma (PCC) we utilize a well-annotated hereditary cancer testing database. METHODS: Records of 120,061 patients receiving germline testing were obtained. FH variants were classified into 4 categories: autosomal dominant (AD) HLRCC variants, autosomal recessive (AR) fumarase deficiency (FMRD), variants, previously reported as PGL/PCC FH variants, and variants of unknown significance (VUS) not previously associated with PGL/PCC (NPP-VUS). Rates of PGL/PCC were compared with those with negative genetic testing. RESULTS: About 1.3% of individuals carried FH variants which were more common among individuals with PGL/PCC compared to those without (3.1% vs 1.3%, P < .0001). PGL/PCC rates were higher among individuals with PGL/PCC FH variants compared to those with negative genetic testing (22.2% vs 0.9%, P < .0001). Neither AD HLRCC variants (0.3% vs 0.9%, P = .35) nor AR FMRD variants (1.4% vs 0.9%, P = .19) carried an increased prevalence of PGL/PCC. An increased prevalence of PGL/PCC was detected in those with NPP-VUS (2.0% vs 0.9%, P = .0023). CONCLUSIONS: Certain FH variants confer an increased risk of PGL/PCC, but not necessarily HLRCC. While universal screening for PGL/PCC among all individuals with FH variants does not appear warranted, it should be considered in select high-risk PGL/PCC FH variants.

Rates and Classification of Variants of Uncertain Significance in Hereditary Disease Genetic Testing.

Importance: Variants of uncertain significance (VUSs) are rampant in clinical genetic testing, frustrating clinicians, patients, and laboratories because the uncertainty hinders diagnoses and clinical management. A comprehensive assessment of VUSs across many disease genes is needed to guide efforts to reduce uncertainty. Objective: To describe the sources, gene distribution, and population-level attributes of VUSs and to evaluate the impact of the different types of evidence used to reclassify them. Design, Setting, and Participants: This cohort study used germline DNA variant data from individuals referred by clinicians for diagnostic genetic testing for hereditary disorders. Participants included individuals for whom gene panel testing was conducted between September 9, 2014, and September 7, 2022. Data were analyzed from September 1, 2022, to April 1, 2023. Main Outcomes and Measures: The outcomes of interest were VUS rates (stratified by age; clinician-reported race, ethnicity, and ancestry groups; types of gene panels; and variant attributes), percentage of VUSs reclassified as benign or likely benign vs pathogenic or likely pathogenic, and enrichment of evidence types used for reclassifying VUSs. Results: The study cohort included 1 689 845 individuals ranging in age from 0 to 89 years at time of testing (median age, 50 years), with 1 203 210 (71.2%) female individuals. There were 39 150 Ashkenazi Jewish individuals (2.3%), 64 730 Asian individuals (3.8%), 126 739 Black individuals (7.5%), 5539 French Canadian individuals (0.3%), 169 714 Hispanic individuals (10.0%), 5058 Native American individuals (0.3%), 2696 Pacific Islander individuals (0.2%), 4842 Sephardic Jewish individuals (0.3%), and 974 383 White individuals (57.7%). Among all individuals tested, 692 227 (41.0%) had at least 1 VUS and 535 385 (31.7%) had only VUS results. The number of VUSs per individual increased as more genes were tested, and most VUSs were missense changes (86.6%). More VUSs were observed per sequenced gene in individuals who were not from a European White population, in middle-aged and older adults, and in individuals who underwent testing for disorders with incomplete penetrance. Of 37 699 unique VUSs that were reclassified, 30 239 (80.2%) were ultimately categorized as benign or likely benign. A mean (SD) of 30.7 (20.0) months elapsed for VUSs to be reclassified to benign or likely benign, and a mean (SD) of 22.4 (18.9) months elapsed for VUSs to be reclassified to pathogenic or likely pathogenic. Clinical evidence contributed most to reclassification. Conclusions and Relevance: This cohort study of approximately 1.6 million individuals highlighted the need for better methods for interpreting missense variants, increased availability of clinical and experimental evidence for variant classification, and more diverse representation of race, ethnicity, and ancestry groups in genomic databases. Data from this study could provide a sound basis for understanding the sources and resolution of VUSs and navigating appropriate next steps in patient care.

Retrospective Cohort Study on the Limitations of Direct-to-Consumer Genetic Screening in Hereditary Breast and Ovarian Cancer.

PURPOSE: Among cancer predisposition genes, most direct-to-consumer (DTC) genetic tests evaluate three Ashkenazi Jewish (AJ) founder mutations in BRCA1/2, which represent a small proportion of pathogenic or likely pathogenic variants (PLPV) in cancer predisposing genes. In this study, we investigate PLPV in BRCA1/2 and other cancer predisposition genes that are missed by testing only AJ founder BRCA1/2 mutations. METHODS: Individuals were referred to genetic testing for personal diagnoses of breast and/or ovarian cancer (clinical cohort) or were self-referred (nonindication-based cohort). There were 348,692 participants in the clinical cohort and 7,636 participants in the nonindication-based cohort. Both cohorts were analyzed for BRCA1/2 AJ founder mutations. Full sequence analysis was done for PLPV in BRCA1/2, CDH1, PALB2, PTEN, STK11, TP53, ATM, BARD1, BRIP1, CHEK2 (truncating variants), EPCAM, MLH1, MSH2/6, NF1, PMS2, RAD51C/D, and 22 other genes. RESULTS: BRCA1/2 AJ founder mutations accounted for 10.8% and 29.7% of BRCA1/2 PLPV in the clinical and nonindication-based cohorts, respectively. AJ founder mutations accounted for 89.9% of BRCA1/2 PLPV in those of full AJ descent, but only 69.6% of those of partial AJ descent. In total, 0.5% of all individuals had a BRCA1/2 AJ founder variant, while 7.7% had PLPV in a high-risk breast/ovarian cancer gene. For non-AJ individuals, limiting evaluation to the AJ founder BRCA1/2 mutations missed >90% of mutations in actionable cancer risk genes. Secondary analysis revealed a false-positive rate of 69% for PLPV outside of non-AJ BRCA 1/2 founder mutations. CONCLUSION: DTC genetic testing misses >90% of BRCA1/2 PLPV in individuals of non-AJ ancestry and about 10% of BRCA1/2 PLPV among AJ individuals. There is a high false-positivity rate for non-AJ BRCA 1/2 PLPV with DTC genetic testing.

Efficacy of National Comprehensive Cancer Network Guidelines in Identifying Pathogenic Germline Variants Among Unselected Patients with Prostate Cancer: The PROCLAIM Trial.

BACKGROUND: Prostate cancer (PCa) patients with pathogenic/likely pathogenic germline variants (PGVs) in cancer predisposition genes may be eligible for U.S. Food and Drug Administration-approved targeted therapies, clinical trials, or enhanced screening. Studies suggest that eligible patients are missing genetics-informed care due to restrictive testing criteria. OBJECTIVE: To establish the prevalence of actionable PGVs among prospectively accrued, unselected PCa patients, stratified by their guideline eligibility. DESIGN, SETTING, AND PARTICIPANTS: Consecutive, unselected PCa patients were enrolled at 15 sites in the USA from October 2019 to August 2021, and had multigene cancer panel testing. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Correlates between the prevalence of PGVs and clinician-reported demographic and clinical characteristics were examined. RESULTS AND LIMITATIONS: Among 958 patients (median [quartiles] age at diagnosis 65 [60, 71] yr), 627 (65%) had low- or intermediate-risk disease (grade group 1, 2, or 3). A total of 77 PGVs in 17 genes were identified in 74 patients (7.7%, 95% confidence interval [CI] 6.2-9.6%). No significant difference was found in the prevalence of PGVs among patients who met the 2019 National Comprehensive Cancer Network Prostate criteria (8.8%, 43/486, 95% CI 6.6-12%) versus those who did not (6.6%, 31/472, 95% CI 4.6-9.2%; odds ratio 1.38, 95% CI 0.85-2.23), indicating that these criteria would miss 42% of patients (31/74, 95% CI 31-53%) with PGVs. The criteria were less effective at predicting PGVs in patients from under-represented populations. Most PGVs (81%, 60/74) were potentially clinically actionable. Limitations include the inability to stratify analyses based on individual ethnicity due to low numbers of non-White patients with PGVs. CONCLUSIONS: Our results indicate that almost half of PCa patients with PGVs are missed by current testing guidelines. Comprehensive germline genetic testing should be offered to all patients with PCa. PATIENT SUMMARY: One in 13 patients with prostate cancer carries an inherited variant that may be actionable for the patient's current care or prevention of future cancer, and could benefit from expanded testing criteria.

Multigene Panel Testing Yields High Rates of Clinically Actionable Variants Among Patients With Colorectal Cancer.

PURPOSE: Whether germline multigene panel testing (MGPT) should be performed in all individuals with colorectal cancer (CRC) remains uncertain. Therefore, we aimed to determine the yield and potential clinical impact of MGPT across a large, diverse CRC cohort. METHODS: This was a retrospective cohort study of adults with CRC who underwent MGPT of > 10 genes at a commercial laboratory between March 2015 and May 2021. All data were prospectively collected through a single commercial laboratory and retrospectively analyzed. RESULTS: A total of 34,244 individuals with a history of CRC underwent germline MPGT and were included in the analysis. This cohort was predominantly female (60.7%), White (70.6%), and age 50 years or older (68.9%), with 35.5% also reporting a noncolorectal malignancy. At least one pathogenic/likely pathogenic germline variant (PGV) was found in 4,864 (14.2%), with 3,111 (9.1%) having a PGV associated with increased CRC/polyposis risk and 1,048 (3.1%) having an otherwise clinically actionable PGV. Larger gene panels were not clearly associated with higher yield of clinically actionable PGVs. PGVs were more prevalent in individuals of Ashkenazi Jewish descent (P < .001) and Hispanic ethnicity (P < .001). Across all ages, panel sizes, and races/ethnicities, the rate of clinically actionable PGVs on MGPT was 7.9% or greater. A variant of uncertain significance was identified in 13,094 individuals (38.2%). Identification of a variant of uncertain significance associated with panel size (P < .001) and was lower in individuals of Ashkenazi Jewish descent (P < .001), but higher in Black, Asian, and Hispanic individuals (P < .001). CONCLUSION: To our knowledge, this is the largest study to date examining MGPT in CRC, demonstrating high rates of clinically actionable variants detected across all age groups, panel sizes, and racial/ethnic groups. This work supports consideration of broadening germline genetic testing criteria for individuals with CRC.

Ashkenazi Jewish and Other White APC I1307K Carriers Are at Higher Risk for Multiple Cancers.

Purpose: APC I1307K has a higher prevalence among Ashkenazi Jews (AJ), and a two-fold increased risk for colorectal cancer (CRC) compared to non-Jewish populations. We assessed CRC and extracolonic malignancies among I1307K carriers from AJ and non-AJ whites (NAW). Methods: We compared the rate of I1307K in cancer patients who underwent germline genetic testing via a multi-gene panel with healthy subjects retrieved from the gnomAD database. Cases undergoing testing were not selected and testing was undertaken through a commercial laboratory. Results: Overall, 586/7624 (7.6%) AJ with cancer carried I1307K compared to 342/4918 (6.9%) in the AJ control group (p = NS). In the NAW, 318/141,673 (0.2%) cancer patients and 73/58,918 (0.1%) controls carried the variant [OR = 1.8, (95% CI 1.41−2.35), p < 0.001]. I1307K in NAW was associated with an increased risk of CRC [OR = 1.95, (95% CI 1.39−2.73), p < 0.01], melanoma [OR = 2.54, (95% CI 1.57−3.98)], breast [females, OR = 1.73, (95% CI 1.18−2.65), p < 0.01], and prostate cancer [males, OR = 2.42, (95% CI 1.45−3.94), p < 0.01]. Among AJ, the variant increased the risk for CRC [OR = 1.67, (95% CI 1.36−2.05), p < 0.001] and renal cancer [OR = 1.64, (95% CI 1.04−2.47)]. AJ men had a higher risk for any cancer [OR = 1.32, (95% CI 1.05−1.66), p < 0.05] and melanoma [OR = 2.04, (95% CI 1.24−3.22); p < 0.05]. Conclusions: This is the most extensive study to date conducted on I1307K carriers, although it is amenable to selection bias. NAW carrying I1307K had a higher risk of any cancer and several specific cancer types, whereas AJ carrying the variant had a risk for only a few select cancers. Our data add to the research base on I1307 carriers concerning future risk management.

Re-evaluating cancer risks associated with the CHEK2 p.Ser428Phe Ashkenazi Jewish founder pathogenic variant.

A missense variant (p.Ser428Phe [S428F]) in the CHEK2 gene is reportedly associated with a 2-3 fold increase in breast cancer risk in Ashkenazi Jews. This study aimed to re-evaluate cancer risks conferred by the CHEK2 S428F variant in Ashkenazi Jews. De-identified data from CHEK2 S428F variant carriers sequenced with multigene panels were analyzed. Overall, 486/341,531 (0.14%) cases of all ethnicities diagnosed with any cancer type were CHEK2 S428F carriers, of whom 243/9980 self-identified as Ashkenazi Jews and carried this risk variant only. Compared with ethnically matched non-cancer controls, across all cancer cases, this variant was not more prevalent (p = 0.271). Specifically, variant prevalence was not different in breast cancer cases compared with controls. Though the variant was shown to be enriched in pancreatic cancer cases (p = 0.008), sample size was small. The CHEK2 S428F variant was not overrepresented in Ashkenazi Jews with breast cancer and most other cancer types analyzed, except for pancreatic cancer, compared with ethnically matched non- cancer controls. These findings should prompt reevaluating ethnic-specific CHEK2 S428F cancer attributable risk.

The Impact of Proband Indication for Genetic Testing on the Uptake of Cascade Testing Among Relatives.

Although multiple factors can influence the uptake of cascade genetic testing, the impact of proband indication has not been studied. We performed a retrospective, cross-sectional study comparing cascade genetic testing rates among relatives of probands who received either diagnostic germline testing or non-indication-based proactive screening via next-generation sequencing (NGS)-based multigene panels for hereditary cancer syndromes (HCS) and/or familial hypercholesterolemia (FH). The proportion of probands with a medically actionable (positive) finding were calculated based on genes associated with Centers for Disease Control and Prevention (CDC) Tier 1 conditions, HCS genes, and FH genes. Among probands with a positive finding, cascade testing rates and influencing factors were assessed. A total of 270,715 probands were eligible for inclusion in the study (diagnostic n = 254,281,93.9%; proactive n = 16,434, 6.1%). A positive result in a gene associated with a CDC Tier 1 condition was identified in 10,520 diagnostic probands (4.1%) and 337 proactive probands (2.1%), leading to cascade testing among families of 3,305 diagnostic probands (31.4%) and 36 proactive probands (10.7%) (p < 0.0001). A positive result in an HCS gene was returned to 23,272 diagnostic probands (9.4%) and 970 proactive probands (6.1%), leading to cascade testing among families of 6,611 diagnostic probands (28.4%) and 89 proactive probands (9.2%) (p < 0.0001). Cascade testing due to a positive result in an HCS gene was more commonly pursued when the diagnostic proband was White, had a finding in a gene associated with a CDC Tier 1 condition, or had a personal history of cancer, or when the proactive proband was female. A positive result in an FH gene was returned to 1,647 diagnostic probands (25.3%) and 67 proactive probands (0.62%), leading to cascade testing among families of 360 diagnostic probands (21.9%) and 4 proactive probands (6.0%) (p < 0.01). Consistently higher rates of cascade testing among families of diagnostic probands may be due to a perceived urgency because of personal or family history of disease. Due to the proven clinical benefit of cascade testing, further research on obstacles to systematic implementation and uptake of testing for relatives of any proband with a medically actionable variant is warranted.