Reanalysis of eMERGE phase III sequence variants in 10,500 participants and infrastructure to support the automated return of knowledge updates

Potentially Missed Diagnoses in Prenatal Versus Postnatal Exome Sequencing in the Lack of Informative Phenotype: Lessons Learned From a Postnatal Cohort

OBJECTIVE

To investigate how many novel pathogenic (P) and likely pathogenic (LP) nonprotein-truncating or noncanonical splicing variants would be classified as variants of unknown significance (VUS) if they were detected in fetuses without abnormalities.

METHODS

The study included 156 patients with neurodevelopmental disorders diagnosed through postnatal exome sequencing. Causative P/LP nonprotein-truncating and noncanonical splicing variants were retrospectively reclassified in cases without specific prenatal manifestations, disregarding postnatal symptoms.

RESULTS

Of the 156 patients, 72 had a nontruncating or noncanonical splicing variant. Six patients were excluded for having more than one possible causative variant. Twelve patients had prenatal malformations known to be associated with the diagnosed disorder; therefore, variant interpretation remained unchanged. In 33 of the 54 remaining cases, the variant had been previously reported as P/LP. Reclassification of the other 21 LP/P variants revealed that 16 would have been classified as VUS if detected prenatally.

CONCLUSION

In our cohort, ∼24% (16/66) of causative nonprotein-truncating/noncanonical splicing variants would have been classified as VUS if sequencing had been conducted during pregnancy. The potential for false-negative results, stemming from limitations in the phenotypic information available prenatally, should be discussed with prospective parents. The criteria for classifying and reporting variants in the prenatal setting may require adjustment.

Variant reclassification and recontact research: A scoping review

Purpose

A primary challenge in clinical genetics is accurate interpretation of identified variants and relaying the information to patients and providers. Inconsistencies around handling variant reclassifications and notifying patients, combined with the lack of prescriptive guidelines on re-evaluation, reanalysis, and return of variants, has created practice challenges. Although relevant empirical work has emerged, the scope and outcomes of this research have not been characterized.

Methods

We conducted a systematic literature review of variant reclassification and recontact research (2013-2023) across subdisciplines of medical genetics. Of the 159 nonduplicate records screened, we summarize findings from 54 included research articles describing variant reclassification frequencies, outcomes, and stakeholder perspectives on recontact.

Results

The included articles reported on active reclassification (n = 20), passive reclassification (n = 13), stakeholder surveys (n = 11), qualitative interviews (n = 7), and reanalysis of published or ClinVar data (n = 3). On average, active and passive approaches yielded different reclassification frequencies-31% and 20%, respectively, which were considerably higher than ClinVar (<0.1%-6.4%). Despite a wealth of data on individual stakeholder perspectives and opinions on reclassification, recontact, and consensus on the need for standardization in this space, opinions differ on how to develop and implement standardized processes.

Conclusion

Many active reclassification studies reapplied standard variant classification guideline to previously reported variants-thus demonstrating the number of variants that would be successfully reclassified if reinterpretation and reanalysis were performed routinely. Research gaps identified include the need for understanding practices and opinions of nongenetics providers and engaging in deliberative democracy exercises to reach consensus on these issues.

Variant reclassification and clinical implications

Genomic technologies have transformed clinical genetic testing, underlining the importance of accurate molecular genetic diagnoses. Variant classification, ranging from benign to pathogenic, is fundamental to these tests. However, variant reclassification, the process of reassigning the pathogenicity of variants over time, poses challenges to diagnostic legitimacy. This review explores the medical and scientific literature available on variant reclassification, focusing on its clinical implications.Variant reclassification is driven by accruing evidence from diverse sources, leading to variant reclassification frequency ranging from 3.6% to 58.8%. Recent studies have shown that significant changes can occur when reviewing variant classifications within 1 year after initial classification, illustrating the importance of early, accurate variant assignation for clinical care.Variants of uncertain significance (VUS) are particularly problematic. They lack clear categorisation but have influenced patient treatment despite recommendations against it. Addressing VUS reclassification is essential to enhance the credibility of genetic testing and the clinical impact. Factors affecting reclassification include standardised guidelines, clinical phenotype-genotype correlations through deep phenotyping and ancestry studies, large-scale databases and bioinformatics tools. As genomic databases grow and knowledge advances, reclassification rates are expected to change, reducing discordance in future classifications.Variant reclassification affects patient diagnosis, precision therapy and family screening. The exact patient impact is yet unknown. Understanding influencing factors and adopting standardised guidelines are vital for precise molecular genetic diagnoses, ensuring optimal patient care and minimising clinical risk.

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.

Evaluating the association of biallelic OGDHL variants with significant phenotypic heterogeneity

BACKGROUND

Biallelic variants in OGDHL, encoding part of the α-ketoglutarate dehydrogenase complex, have been associated with highly heterogeneous neurological and neurodevelopmental disorders. However, the validity of this association remains to be confirmed. A second OGDHL patient cohort was recruited to carefully assess the gene-disease relationship.

METHODS

Using an unbiased genotype-first approach, we screened large, multiethnic aggregated sequencing datasets worldwide for biallelic OGDHL variants. We used CRISPR/Cas9 to generate zebrafish knockouts of ogdhl, ogdh paralogs, and dhtkd1 to investigate functional relationships and impact during development. Functional complementation with patient variant transcripts was conducted to systematically assess protein functionality as a readout for pathogenicity.

RESULTS

A cohort of 14 individuals from 12 unrelated families exhibited highly variable clinical phenotypes, with the majority of them presenting at least one additional variant, potentially accounting for a blended phenotype and complicating phenotypic understanding. We also uncovered extreme clinical heterogeneity and high allele frequencies, occasionally incompatible with a fully penetrant recessive disorder. Human cDNA of previously described and new variants were tested in an ogdhl zebrafish knockout model, adding functional evidence for variant reclassification. We disclosed evidence of hypomorphic alleles as well as a loss-of-function variant without deleterious effects in zebrafish variant testing also showing discordant familial segregation, challenging the relationship of OGDHL as a conventional Mendelian gene. Going further, we uncovered evidence for a complex compensatory relationship among OGDH, OGDHL, and DHTKD1 isoenzymes that are associated with neurodevelopmental disorders and exhibit complex transcriptional compensation patterns with partial functional redundancy.

CONCLUSIONS

Based on the results of genetic, clinical, and functional studies, we formed three hypotheses in which to frame observations: biallelic OGDHL variants lead to a highly variable monogenic disorder, variants in OGDHL are following a complex pattern of inheritance, or they may not be causative at all. Our study further highlights the continuing challenges of assessing the validity of reported disease-gene associations and effects of variants identified in these genes. This is particularly more complicated in making genetic diagnoses based on identification of variants in genes presenting a highly heterogenous phenotype such as "OGDHL-related disorders".

Diagnostic yield and clinical relevance of expanded genetic testing for cancer patients

BACKGROUND

Genetic testing (GT) for hereditary cancer predisposition is traditionally performed on selected genes based on established guidelines for each cancer type. Recently, expanded GT (eGT) using large hereditary cancer gene panels uncovered hereditary predisposition in a greater proportion of patients than previously anticipated. We sought to define the diagnostic yield of eGT and its clinical relevance in a broad cancer patient population over a 5-year period.

METHODS

A total of 17,523 cancer patients with a broad range of solid tumors, who received eGT at Memorial Sloan Kettering Cancer Center between July 2015 to April 2020, were included in the study. The patients were unselected for current GT criteria such as cancer type, age of onset, and/or family history of disease. The diagnostic yield of eGT was determined for each cancer type. For 9187 patients with five common cancer types frequently interrogated for hereditary predisposition (breast, colorectal, ovarian, pancreatic, and prostate cancer), the rate of pathogenic/likely pathogenic (P/LP) variants in genes that have been associated with each cancer type was analyzed. The clinical implications of additional findings in genes not known to be associated with a patients' cancer type were investigated.

RESULTS

16.7% of patients in a broad cancer cohort had P/LP variants in hereditary cancer predisposition genes identified by eGT. The diagnostic yield of eGT in patients with breast, colorectal, ovarian, pancreatic, and prostate cancer was 17.5%, 15.3%, 24.2%, 19.4%, and 15.9%, respectively. Additionally, 8% of the patients with five common cancers had P/LP variants in genes not known to be associated with the patient's current cancer type, with 0.8% of them having such a variant that confers a high risk for another cancer type. Analysis of clinical and family histories revealed that 74% of patients with variants in genes not associated with their current cancer type but which conferred a high risk for another cancer did not meet the current GT criteria for the genes harboring these variants. One or more variants of uncertain significance were identified in 57% of the patients.

CONCLUSIONS

Compared to targeted testing approaches, eGT can increase the yield of detection of hereditary cancer predisposition in patients with a range of tumors, allowing opportunities for enhanced surveillance and intervention. The benefits of performing eGT should be weighed against the added number of VUSs identified with this approach.

Managing Pandora's Box: Familial Expectations around the Return of (Future) Germline Results

BACKGROUND

Pediatric oncology patients are increasingly being offered germline testing to diagnose underlying cancer predispositions. Meanwhile, as understanding of variant pathogenicity evolves, planned reanalysis of genomic results has been suggested. Little is known regarding the types of genomic information that parents and their adolescent children with cancer prefer to receive at the time of testing or their expectations around the future return of genomic results.

METHODS

Parents and adolescent children with cancer eligible for genomic testing for cancer predisposition were surveyed regarding their attitudes and expectations for receiving current and future germline results (ClinicalTrials.gov Identifier: NCT02530658).

RESULTS

All parents (100%) desired to learn about results for treatable or preventable conditions, with 92.4% wanting results even when there is no treatment or prevention. Parents expressed less interest in receiving uncertain results for themselves (88.3%) than for their children (95.3%). Most parents (95.9%) and adolescents (87.9%) believed that providers have a responsibility to share new or updated germline results indefinitely or at any point during follow-up care. Fewer parents (67.5%) indicated that they would want results if their child was deceased: 10.3% would not want to be contacted, 19.3% were uncertain.

CONCLUSIONS

Expectations for return of new or updated genomic results are high among pediatric oncology families, although up to one third of parents have reservations about receiving such information in the event of their child's death. These results underscore the importance of high-quality pre-and post-test counseling, conducted by individuals trained in consenting around genomic testing to elicit family preferences and align expectations around the return of germline results.