Podcast
Questions and Answers
What should genotype-driven analyses aim to capture regarding variants?
What should genotype-driven analyses aim to capture regarding variants?
Genotype-driven analyses should aim to capture all variants that may be classified as pathogenic or likely pathogenic.
What types of variants are prioritized during the analysis of multiple family members?
What types of variants are prioritized during the analysis of multiple family members?
Variants suspected based on their inheritance pattern, such as de novo variants or biallelic rare variants, are prioritized.
Why are clinical laboratories encouraged to include analysis of genes not yet linked to disease?
Why are clinical laboratories encouraged to include analysis of genes not yet linked to disease?
Including such analysis may help in discovering novel disease genes and aid in understanding genotype-phenotype correlations.
What challenges exist in the automated prioritization of pathogenic variants?
What challenges exist in the automated prioritization of pathogenic variants?
How can software tools assist analysts in identifying variants with disease associations?
How can software tools assist analysts in identifying variants with disease associations?
What role does the ClinVar database play in genotype-phenotype analysis?
What role does the ClinVar database play in genotype-phenotype analysis?
What types of variants are highlighted in automated prioritization based on gnomAD constraint scores?
What types of variants are highlighted in automated prioritization based on gnomAD constraint scores?
How should genotype-driven analysis be supplemented for comprehensive results?
How should genotype-driven analysis be supplemented for comprehensive results?
What is the importance of phenotype-driven and genotype-driven filtering strategies in reviewing single nucleotide variants?
What is the importance of phenotype-driven and genotype-driven filtering strategies in reviewing single nucleotide variants?
What are the potential outcomes from applying an unbiased analysis approach to variant detection?
What are the potential outcomes from applying an unbiased analysis approach to variant detection?
Why is it important to consider all possible consequences of single nucleotide variants?
Why is it important to consider all possible consequences of single nucleotide variants?
What types of genetic diagnoses can be revealed through the analysis of single nucleotide variants?
What types of genetic diagnoses can be revealed through the analysis of single nucleotide variants?
What role do resources like ClinGen play in the identification of high-frequency variants?
What role do resources like ClinGen play in the identification of high-frequency variants?
What is meant by phenotypic expansion in the context of variant analysis?
What is meant by phenotypic expansion in the context of variant analysis?
What are the implications of finding clinically significant incidental or secondary findings?
What are the implications of finding clinically significant incidental or secondary findings?
What challenges are associated with multi-allelic variants in single nucleotide variant analysis?
What challenges are associated with multi-allelic variants in single nucleotide variant analysis?
What is the primary advantage of whole genome sequencing (WGS) compared to other sequencing methods?
What is the primary advantage of whole genome sequencing (WGS) compared to other sequencing methods?
What types of genetic variants can be detected by whole genome sequencing?
What types of genetic variants can be detected by whole genome sequencing?
How does WGS ensure uniform coverage of genomic regions?
How does WGS ensure uniform coverage of genomic regions?
What was the purpose of the Medical Genome Initiative's working group?
What was the purpose of the Medical Genome Initiative's working group?
What discrepancy was noted between whole exome sequencing (WES) and whole genome sequencing (WGS) in the recent meta-analysis?
What discrepancy was noted between whole exome sequencing (WES) and whole genome sequencing (WGS) in the recent meta-analysis?
What methods were used to guide the discussions and development of the best practice recommendations?
What methods were used to guide the discussions and development of the best practice recommendations?
What should newly issued test requisition forms indicate regarding genetic variants?
What should newly issued test requisition forms indicate regarding genetic variants?
What are some of the key areas that lack consensus in the adoption of WGS?
What are some of the key areas that lack consensus in the adoption of WGS?
How might laboratories suggest a time period for reanalysis of genetic tests?
How might laboratories suggest a time period for reanalysis of genetic tests?
Why might comparisons between cohorts in genetic sequencing be limited in utility?
Why might comparisons between cohorts in genetic sequencing be limited in utility?
What triggers reactive reanalysis in a laboratory setting?
What triggers reactive reanalysis in a laboratory setting?
In what way can reanalysis be initiated proactively?
In what way can reanalysis be initiated proactively?
What is the importance of clarifying phenotypic data before testing?
What is the importance of clarifying phenotypic data before testing?
What is the role of policies regarding secondary findings in genetic testing?
What is the role of policies regarding secondary findings in genetic testing?
What should requisition and consent forms clarify for trio or multiple-family member sequencing?
What should requisition and consent forms clarify for trio or multiple-family member sequencing?
Why is proactive reanalysis recognized as an important step in WGS testing?
Why is proactive reanalysis recognized as an important step in WGS testing?
What is the recommended process for reviewing monoallelic variants in autosomal recessive genes?
What is the recommended process for reviewing monoallelic variants in autosomal recessive genes?
Why is it important for automated analysis tools to be assessed by human analysts?
Why is it important for automated analysis tools to be assessed by human analysts?
What should be included in laboratory policies regarding findings considered for return?
What should be included in laboratory policies regarding findings considered for return?
What tools are recommended for systematic proactive reanalysis of variants?
What tools are recommended for systematic proactive reanalysis of variants?
How should results from automated analyses be handled before reporting?
How should results from automated analyses be handled before reporting?
What is the goal of the laboratory's reporting policies?
What is the goal of the laboratory's reporting policies?
What type of evidence should be addressed when returning variant findings?
What type of evidence should be addressed when returning variant findings?
Why is open communication encouraged between ordering providers and the laboratory?
Why is open communication encouraged between ordering providers and the laboratory?
What is the primary role of automated phenotyping in clinical genome sequencing?
What is the primary role of automated phenotyping in clinical genome sequencing?
What are copy-number variants and why are they significant in genetic disorders?
What are copy-number variants and why are they significant in genetic disorders?
How does Face2Gene facilitate the identification of genetic syndromes?
How does Face2Gene facilitate the identification of genetic syndromes?
What is the significance of structural variation reference in medical genetics?
What is the significance of structural variation reference in medical genetics?
What are the main challenges in detecting long-read assemblies from short-read genome sequencing technologies?
What are the main challenges in detecting long-read assemblies from short-read genome sequencing technologies?
Why is the Human Disease Ontology significant in genetic research?
Why is the Human Disease Ontology significant in genetic research?
Describe the ethical considerations involved in handling incidental findings in genetic testing.
Describe the ethical considerations involved in handling incidental findings in genetic testing.
What role do guidelines such as those from ACMG/AMP play in mitochondrial DNA variant interpretation?
What role do guidelines such as those from ACMG/AMP play in mitochondrial DNA variant interpretation?
Flashcards
What is Whole Genome Sequencing (WGS)?
What is Whole Genome Sequencing (WGS)?
Whole Genome Sequencing (WGS) is a powerful technique that allows scientists to analyze the complete DNA sequence of an organism, offering a comprehensive view of an individual's genetic makeup. It provides a more detailed picture of variations compared to targeted sequencing, enabling the detection of a wide range of genetic alterations like SNVs, insertions, deletions, mitochondrial variants.
What are the benefits of WGS over other genetic testing?
What are the benefits of WGS over other genetic testing?
WGS goes beyond just looking at genes, it also analyzes non-coding regions (introns, intergenic regions) which may play important roles in regulating gene expression and disease development.
What types of genetic variations can WGS detect?
What types of genetic variations can WGS detect?
WGS allows the detection of a broader range of variants, including small insertions and deletions, mitochondrial variants, repeat expansions, copy number variants, and other structural variants.
How is WGS used in diagnostics?
How is WGS used in diagnostics?
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How does WGS contribute to personalized medicine?
How does WGS contribute to personalized medicine?
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Who is working to standardize WGS for clinical use?
Who is working to standardize WGS for clinical use?
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What are the key areas of focus for the MGI working group?
What are the key areas of focus for the MGI working group?
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Why are best practice recommendations for WGS important?
Why are best practice recommendations for WGS important?
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Single Nucleotide Variants (SNVs)
Single Nucleotide Variants (SNVs)
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Phenotype-driven filtering
Phenotype-driven filtering
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Genotype-driven filtering
Genotype-driven filtering
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Multi-allelic variants
Multi-allelic variants
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Splicing annotations
Splicing annotations
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High frequency variants
High frequency variants
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ClinGen and GeT-RM
ClinGen and GeT-RM
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Low penetrance, risk, and other high frequency variants
Low penetrance, risk, and other high frequency variants
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Genotype-Driven Analysis
Genotype-Driven Analysis
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Predicted Loss of Function (pLOF) Variant
Predicted Loss of Function (pLOF) Variant
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Gene Discovery Analysis
Gene Discovery Analysis
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ClinVar
ClinVar
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gnomAD
gnomAD
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Phenotype-Driven Analysis
Phenotype-Driven Analysis
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Judicious Reporting
Judicious Reporting
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De Novo Variant
De Novo Variant
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Copy Number Variant (CNV)
Copy Number Variant (CNV)
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Re-examination of Calls
Re-examination of Calls
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Proactive Reanalysis
Proactive Reanalysis
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Human Analyst Assessment
Human Analyst Assessment
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Reporting Policies
Reporting Policies
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Variant Penetrance
Variant Penetrance
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Open Reporting Communication
Open Reporting Communication
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Reanalysis of WGS data
Reanalysis of WGS data
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Minimum time period for reanalysis
Minimum time period for reanalysis
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Trio sequencing
Trio sequencing
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Phenotype information
Phenotype information
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Policies for secondary findings reporting in WGS
Policies for secondary findings reporting in WGS
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Informed consent for phenotypic data
Informed consent for phenotypic data
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Copy-number variants (CNVs)
Copy-number variants (CNVs)
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Whole-genome sequencing (WGS)
Whole-genome sequencing (WGS)
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PhenoTips
PhenoTips
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Study Notes
Best Practices for Clinical Whole Genome Sequencing
- Whole genome sequencing (WGS) is emerging as a first-tier diagnostic test for rare genetic disorders, offering a more comprehensive approach than whole exome sequencing or other targeted sequencing assays.
- WGS is superior because it can detect a broader range of variant types like single nucleotide variants (SNVs), insertions/deletions, mitochondrial variants, repeat expansions, copy number variants (CNVs) and other structural variants (SVs) within a single assay. It also provides more uniform coverage of exonic regions and intronic, intergenic, and regulatory regions.
- The Medical Genome Initiative (MGI) developed best practice recommendations for WGS interpretation and reporting, focusing on the interpretation and reporting of clinical diagnostic WGS.
Clinical Diagnostic Genomic Sequencing Phases
- Analysis is divided into three phases:
- Primary analysis: technical components of the assay like DNA extraction, library preparation, sequence generation, and preliminary data quality control (QC)
- Secondary analysis: bioinformatic processes such as aligning raw sequence data to a genome reference, variant calling, and other similar processes
- Tertiary analysis: includes annotation, filtering, prioritization, classification of variants, case interpretation, and reporting.
Interpretation and Reporting Considerations for Clinically Relevant Variants
- Single Nucleotide Variants (SNVs): require phenotype-driven and genotype-driven filtering, considering splicing, transcript-specific impacts, and multi-nucleotide variants (MNVs).
- Small Insertions/Deletions (indels): Validation and orthogonal confirmation might be needed for accuracy, prioritizing quality, frequency, and overlap with protein-coding regions.
- Copy Number Variation (CNV): Filtering based on quality, frequency, and overlap with protein-coding regions, and using inheritance and copy number review during triaging. Review of the depth-based plot and B-allele frequency plot across the genome to identify large CNVs is crucial.
- Balanced and Complex Structural Variants (SV): Primarily used for identifying recurrent pathogenic balanced structural variants, refining CNVs, directed SV searches in known regions, and investigating runs of homozygosity (ROH).
- Runs of Homozygosity (ROH): Extensive ROH on a chromosome can indicate uniparental disomy (UPD), while ROH across chromosomes may be due to consanguinity.
- Repeat Expansions: Emphasizes orthogonal testing for repeat length confirmation and visual alignment inspection to confirm allele expansions and identify interruptions.
- Mitochondrial Variants: Focuses on heteroplasmy, heteroplasmy thresholds for disease manifestation, variable inter- and intra-familial phenotype expressivity, and sample origin variations.
- Mosaic Variants: Lower WGS coverage compared to WES or panel testing, indicating a need for orthogonal testing.
- Polygenic Risk Scores (PRS): Should specify ancestry for calculations and acknowledge any limitations based on ancestry in interpretation.
Reanalysis
- Periodic case reanalysis is recommended to improve the diagnostic yield.
- Reanalysis policies should be established in advance and communicate to providers during test ordering.
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