Genome Alert!: A standardized procedure for genomic variant reinterpretation and automated gene-phenotype reassessment in clinical routine

Reclassification of VUS in BRCA1 and BRCA2 using the new BRCA1/BRCA2 ENIGMA track set demonstrates the superiority of ClinGen ENIGMA Expert Panel specifications over the standard ACMG/AMP classification system

Purpose

Variants of uncertain significance (VUS) are considered one of the most significant impediments to the translation of genetic test results into precise clinical recommendations. The 2015 American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) classification guidelines established a general framework for the assessment and classification of genetic variants; yet, gene-specific specifications are needed to enable better variant classification to reduce the number of VUS. The process of gene-specific adaptations of the ACMG/AMP codes is led and accompanied by ClinGen and implemented by Variant Curation Expert Panels (VCEP). The Evidence-based Network for the Interpretation of Germline Mutant Alleles (ENIGMA) VCEP recently published its specifications for the BRCA1 (HGNC:1100) and BRCA2 (HGNC:1101) genes. We investigated the differences in reclassification between the ENIGMA specifications and the standard ACMG/AMP classification system in a clinical setting.

Methods

We reclassified 121 VUS identified in these genes with the latest annotation data using the standard ACMG/AMP classification system and recommendations from the Sequence Variant Interpretation and the ENIGMA specifications. To simplify the reevaluation process, we have created a University of California Santa Cruz Genome Browser track hub that displays the exact data points required for variant classification using the ENIGMA VCEP specifications at the exon and variant level (https://genome.ucsc.edu/s/abenet/BRCA.ENIGMA.hg19).

Results

By comparing the codes used and their different weighting in the 2 approaches, we were able to demonstrate the superiority of the application of ENIGMA VCEP specifications, which resulted in a dramatic reduction of VUS (83.5% ENIGMA VCEP vs 20% ACMG/AMP + Sequence Variant Interpretation).

Conclusion

For the diagnostic analysis of the BRCA1 and BRCA2 genes, the use of the ENIGMA VCEP specifications gives the best possible result in the clinical translation of genetic variants. The University of California Santa Cruz Genome Browser BRCA1/BRCA2 ENIGMA track set significantly simplified the interpretation process.

Canadian College of Medical Geneticists: clinical practice advisory document - responsibility to recontact for reinterpretation of clinical genetic testing

BACKGROUND

Advances in technology and knowledge have facilitated both an increase in the number of patient variants reported and variants reclassified. While there is currently no duty to recontact for reclassified genetic variants, there may be a responsibility. The purpose of this clinical practice advisory document is to provide healthcare practitioners guidance for recontact of previously identified and classified variants, suggest methods for recontact, and principles to consider, taking account patient safety, feasibility, ethical considerations, health service capacity and resource constraints. The target audience are practitioners who order genetic testing, follow patients who have undergone genetic testing and those analysing and reporting genetic testing.

METHODS

A multidisciplinary group of laboratory and ordering clinicians, patient representatives, ethics and legal researchers and a genetic counsellor from the Canadian Association of Genetic Counsellors reviewed the existing literature and guidelines on responsibility to recontact in a clinical context to make recommendations. Comments were collected from the Canadian College of Medical Geneticists (CCMG) Education, Ethics, and Public Policy, Clinical Practice and Laboratory Practice committees, and the membership at large.

RESULTS

Following incorporation of feedback, and external review by the Canadian Association of Genetic Counsellors and patient groups, the document was approved by the CCMG Board of Directors. The CCMG is the Canadian organisation responsible for certifying laboratory and medical geneticists who provide medical genetics services, and for establishing professional and ethical standards for clinical genetics services in Canada.

CONCLUSION

The document describes the ethical and practical factors and suggests a shared responsibility between patients, ordering clinician and laboratory practitioners.

CMAT: ClinVar Mapping and Annotation Toolkit

Summary

Semantic ontology mapping of clinical descriptors with disease outcome is essential. ClinVar is a key resource for human variation with known clinical significance. We present CMAT, a software toolkit and curation protocol for accurately enriching ClinVar releases with disease ontology associations and complex functional consequences.

Availability and implementation

The software and ontology mappings can be obtained from: https://github.com/EBIvariation/CMAT.

Clinical utility of periodic reinterpretation of CNVs of uncertain significance: an 8-year retrospective study

BACKGROUND

Array-CGH is the first-tier genetic test both in pre- and postnatal developmental disorders worldwide. Variants of uncertain significance (VUS) represent around 10~15% of reported copy number variants (CNVs). Even though VUS reanalysis has become usual in practice, no long-term study regarding CNV reinterpretation has been reported.

METHODS

This retrospective study examined 1641 CGH arrays performed over 8 years (2010-2017) to demonstrate the contribution of periodically re-analyzing CNVs of uncertain significance. CNVs were classified using AnnotSV on the one hand and manually curated on the other hand. The classification was based on the 2020 American College of Medical Genetics (ACMG) criteria.

RESULTS

Of the 1641 array-CGH analyzed, 259 (15.7%) showed at least one CNV initially reported as of uncertain significance. After reinterpretation, 106 of the 259 patients (40.9%) changed categories, and 12 of 259 (4.6%) had a VUS reclassified to likely pathogenic or pathogenic. Six were predisposing factors for neurodevelopmental disorder/autism spectrum disorder (ASD). CNV type (gain or loss) does not seem to impact the reclassification rate, unlike the length of the CNV: 75% of CNVs downgraded to benign or likely benign are less than 500 kb in size.

CONCLUSIONS

This study's high rate of reinterpretation suggests that CNV interpretation has rapidly evolved since 2010, thanks to the continuous enrichment of available databases. The reinterpreted CNV explained the phenotype for ten patients, leading to optimal genetic counseling. These findings suggest that CNVs should be reinterpreted at least every 2 years.

A Solve-RD ClinVar-based reanalysis of 1522 index cases from ERN-ITHACA reveals common pitfalls and misinterpretations in exome sequencing

PURPOSE

Within the Solve-RD project (https://solve-rd.eu/), the European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies aimed to investigate whether a reanalysis of exomes from unsolved cases based on ClinVar annotations could establish additional diagnoses. We present the results of the "ClinVar low-hanging fruit" reanalysis, reasons for the failure of previous analyses, and lessons learned.

METHODS

Data from the first 3576 exomes (1522 probands and 2054 relatives) collected from European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies was reanalyzed by the Solve-RD consortium by evaluating for the presence of single-nucleotide variant, and small insertions and deletions already reported as (likely) pathogenic in ClinVar. Variants were filtered according to frequency, genotype, and mode of inheritance and reinterpreted.

RESULTS

We identified causal variants in 59 cases (3.9%), 50 of them also raised by other approaches and 9 leading to new diagnoses, highlighting interpretation challenges: variants in genes not known to be involved in human disease at the time of the first analysis, misleading genotypes, or variants undetected by local pipelines (variants in off-target regions, low quality filters, low allelic balance, or high frequency).

CONCLUSION

The "ClinVar low-hanging fruit" analysis represents an effective, fast, and easy approach to recover causal variants from exome sequencing data, herewith contributing to the reduction of the diagnostic deadlock.

Neuromuscular disorders: finding the missing genetic diagnoses

Neuromuscular disorders (NMDs) are a wide-ranging group of diseases that seriously affect the quality of life of affected individuals. The development of next-generation sequencing revolutionized the diagnosis of NMD, enabling the discovery of hundreds of NMD genes and many more pathogenic variants. However, the diagnostic yield of genetic testing in NMD cohorts remains incomplete, indicating a large number of genetic diagnoses are not identified through current methods. Fortunately, recent advancements in sequencing technologies, analytical tools, and high-throughput functional screening provide an opportunity to circumvent current challenges. Here, we discuss reasons for missing genetic diagnoses in NMD, how emerging technologies and tools can overcome these hurdles, and examine future approaches to improving diagnostic yields in NMD.