Key Points The ClinGen MM-VCEP has specified RUNX1-specific curation rules to address gene function, gene-specific domains, and phenotypic criteria. RUNX1-specific criteria resulted in a reduction in CONF and VUS variants by 33%, emphasizing the need for expert variant curation.

Purpose: The recent growth in pan-ethnic expanded carrier screening (ECS) has raised questions about how such panels might be designed and evaluated systematically. Design principles for ECS panels might improve clinical detection of at-risk couples and facilitate objective discussions of panel choice.Methods: Guided by medical-society statements, we propose a method for the design of ECS panels that aims to maximize the aggregate and per-disease sensitivity and specificity across a range of Mendelian disorders considered serious by a systematic classification scheme. We evaluated this method retrospectively using results from 474,644 de-identified carrier screens. We then constructed several idealized panels to highlight strengths and limitations of different ECS methodologies.Results: Based on modeled fetal risks for "severe" and "profound" diseases, a commercially available ECS panel (Counsyl) is expected to detect 183 affected conceptuses per 100,000 US births. A screen's sensitivity is greatly impacted by two factors: (i) the methodology used (e.g., full-exon sequencing finds more affected conceptuses than targeted genotyping) and (ii) the detection rate of the screen for diseases with high prevalence and complex molecular genetics (e.g., fragile X syndrome). Conclusion:The described approaches enable principled, quantitative evaluation of which diseases and methodologies are appropriate for pan-ethnic expanded carrier screening.

PurposeThe recent growth in pan-ethnic expanded carrier screening (ECS) has raised questions about how such panels might be designed and evaluated systematically. Design principles for ECS panels might improve clinical detection of at-risk couples and facilitate objective discussions of panel choice.MethodsGuided by medical-society statements, we propose a method for the design of ECS panels that aims to maximize the aggregate and per-disease sensitivity and specificity across a range of Mendelian disorders considered serious by a systematic classification scheme. We evaluated this method retrospectively using results from 474,644 de-identified carrier screens. We then constructed several idealized panels to highlight strengths and limitations of different ECS methodologies.ResultsBased on modeled fetal risks for “severe” and “profound” diseases, a commercially available ECS panel (Counsyl) is expected to detect 183 affected conceptuses per 100,000 US births. A screen’s sensitivity is greatly impacted by two factors: (1) the methodology used (e.g., full-exon sequencing finds more affected conceptuses than targeted genotyping), and (2) the detection rate of the screen for diseases with high prevalence and complex molecular genetics (e.g., fragile X syndrome).ConclusionThe described approaches allow principled, quantitative evaluation of which diseases and methodologies are appropriate for pan-ethnic expanded carrier screening.

Genetic testing is becoming an important part of cancer care, and we wanted to see if genetics care was different between individuals of different backgrounds.• We studied 15,775 diverse patients with cancer who had genetic testing using a test called MSK-IMPACT that was covered by research funding.• Clinically important genetic findings were high in all groups. • However, Black patients were less likely to get recommended counseling compared to White patients. • Even after removing many roadblocks, non-White and especially Black patients were less likely to get recommended genetics care, which may affect their cancer treatments and families.

Background: Despite guidelines recommending genetic counseling for patients with early-onset renal cell carcinoma (RCC), studies interrogating the spectrum of germline mutations and clinical associations in patients with early-onset RCC are lacking. Objective: To define the germline genetic spectrum and clinical associations for patients with early-onset RCC diagnosed at age 46 yr who underwent genetic testing. Design, setting, and participants: We retrospectively identified patients with early-onset RCC who underwent germline testing at our institution from February 2003 to June 2020. Outcome measurement and statistical analysis: The frequency and spectrum of pathogenic/likely pathogenic (P/LP) variants were determined. Clinical characteristics associated with mutation status were analyzed using two-sample comparison (Fisher's exact or x 2 test).Results and limitations: Of 232 patients with early-onset RCC, 50% had non-clearcell histology, including unclassified RCC (12.1%), chromophobe RCC (9.7%), FH-deficient RCC (7.0%), papillary RCC (6.6%), and translocation-associated RCC (4.3%). Overall, 43.5% had metastatic disease. Germline P/LP variants were identified in 41 patients (17.7%), of which 21 (9.1%) were in an RCC-associated gene and 20 (8.6%) in a non-RCC-associated gene, including 17 (7.3%) in DNA damage repair genes such as BRCA1/2, ATM, and CHEK2. Factors associated with RCC P/LP variants include

Background and Aims: Carrier screening for Tay-Sachs disease is performed by sequence analysis of the HEXA gene and/or hexosaminidase A enzymatic activity testing. Enzymatic analysis (EA) has been suggested as the optimal carrier screening method, especially in non-Ashkenazi Jewish (non-AJ) individuals, but its utilization and efficacy have not been fully evaluated in the general population. This study assesses the reliability of EA in comparison with HEXA sequence analysis in non-AJ populations. Methods: Five hundred eight Hispanic and African American patients (516 samples) had EA of their leukocytes performed and 12 of these patients who tested positive by EA (“carriers”) had subsequent HEXA gene sequencing performed. Results: Of the 508 patients, 25 (4.9%) were EA positive and 40 (7.9%) were inconclusive. Of the 12 patients who were sequenced, 11 did not carry a pathogenic variant and one carried a likely deleterious mutation (NM_000520.4(HEXA):c.1510C>T). Conclusions: High inconclusive rates and poor correlation between positive/inconclusive enzyme results and identification of pathogenic mutations suggest that ethnic-specific recalibration of reference ranges for EA may be necessary. Alternatively, HEXA gene sequencing could be performed.

Background Pathogenic variants in HEXA that impair β‐hexosaminidase A (Hex A) enzyme activity cause Tay‐Sachs Disease (TSD), a severe autosomal‐recessive neurodegenerative disorder. Hex A enzyme analysis demonstrates near‐zero activity in patients affected with TSD and can also identify carriers, whose single functional copy of HEXA results in reduced enzyme activity relative to noncarriers. Although enzyme testing has been optimized and widely used for carrier screening in Ashkenazi Jewish (AJ) individuals, it has unproven sensitivity and specificity in a pan‐ethnic population. The ability to detect HEXA variants via DNA analysis has evolved from limited targeting of a few ethnicity‐specific variants to next‐generation sequencing (NGS) of the entire coding region coupled with interpretation of any discovered novel variants. Methods We combined results of enzyme testing, retrospective computational analysis, and variant reclassification to estimate the respective clinical performance of TSD screening via enzyme analysis and NGS. We maximized NGS accuracy by reclassifying variants of uncertain significance and compared to the maximum performance of enzyme analysis estimated by calculating ethnicity‐specific frequencies of variants known to yield false‐positive or false‐negative enzyme results (e.g., pseudodeficiency and B1 alleles). Results In both AJ and non‐AJ populations, the estimated clinical sensitivity, specificity, and positive predictive value were higher by NGS than by enzyme testing. The differences were significant for all comparisons except for AJ clinical sensitivity, where NGS exceeded enzyme testing, but not significantly. Conclusions Our results suggest that performance of an NGS‐based TSD carrier screen that interrogates the entire coding region and employs novel variant interpretation exceeds that of Hex A enzyme testing, warranting a reconsideration of existing guidelines.

Background Li-Fraumeni syndrome (LFS) genetic testing is performed using blood specimens from patients selected based on phenotype-dependent guidelines. This approach is problematic for understanding LFS clinical spectrum, because patients with non-classical presentations are missed, clonal hematopoiesis (CH)-related somatic blood mutations cannot be distinguished from germline variants, and unrelated tumors cannot be differentiated from those driven by germline TP53 defects. Methods To provide insights into LFS-related cancer spectrum, we analyzed paired tumor-blood DNA sequencing results in 17,922 cancer patients, and distinguished CH-related, mosaic, and germline TP53 variants. Loss-of-heterozygosity (LOH) and TP53 mutational status were assessed in tumors, followed by immunohistochemistry for p53 expression on a subset to identify those lacking biallelic TP53 inactivation. Results Pathogenic/likely pathogenic TP53 variants were identified in 50 patients, 12 (24.0%) of which were CH-related and four (8.0%) were mosaic. Twelve (35.3%) of 34 patients with germline TP53 variants did not meet LFS testing criteria. LOH of germline TP53 variant was observed in 96.0% (95% CI = 79.7–99.9%) of core LFS-spectrum type tumors versus 45.5% (95% CI = 16.8–76.6%) of other tumors, and 91.3% (95% CI = 72.0–98.9%) of tumors from patients who met LFS testing criteria versus 61.5% (95% CI = 31.6–86.1%) of tumors from patients who did not. Tumors retaining wild-type TP53 allele exhibited wild-type p53 expression. Conclusions Our results indicate that some TP53 variants identified in blood-only sequencing are not germline and a substantial proportion of LFS patients are missed by current testing guidelines. Additionally, a subset of tumors from LFS patients do not have biallelic TP53 inactivation and may represent cancers unrelated to their germline TP53 defect.