Vídeo 1 Estrutura de Laudo Guilherme Yamamoto

Name: Vídeo 1 Estrutura de Laudo Guilherme Yamamoto
Uploaded: 2024-10-05T23:38:17.000Z
Duration: 1 h 16 min

Introduction to Genetic Testing Reports

Overview of the Course

Guilherme Lopes AM introduces himself as a geneticist and bioinformatics coordinator, outlining his roles at various institutions.

The first lecture focuses on the structure of genetic test reports, particularly for next-generation sequencing (NGS), including exome and genome sequencing.

Regulatory Framework

Reference is made to a technical opinion from the Brazilian Society of Medical Genetics issued in 2020, emphasizing compliance with RDC number 302 from 2005.

The speaker notes that this regulation governs laboratory practices, including report generation and clinical analysis responsibilities.

Essential Components of Genetic Test Reports

Key elements required in a genetic test report include:

Patient identification (full name, date of birth, sex).

Physician's details and laboratory accreditation.

Test name and sample type (e.g., blood, saliva).

Clinical indication for the test must be clearly stated alongside results that are prominently highlighted within the report.

Interpretation and Methodology

The Brazilian Society recommends including variant data for genomic hybridization comparisons and NGS results in reports.

Methodological details should encompass validation information, limitations of tests, references used, and signatures from responsible professionals.

Updates in Regulations

New Guidelines under RDC 736

In 2023, RDC 736 replaced previous regulations but maintains similar requirements regarding clarity and legibility in reports.

Reports must be signed by legally qualified health professionals with proper registration numbers included.

Detailed Report Requirements

Additional necessary components include:

Date of biological material collection.

Analytical method used.

Result units and reference values where applicable.

Key Considerations in Genetic Reporting

Importance of Variant Classification

Emphasis is placed on understanding variant classification as a critical aspect throughout the course.

The classification process involves aggregating all relevant clinical evidence related to variants found during testing.

Understanding Variant Classification in Genetic Testing

Importance of Variant Classification

The classification of genetic variants is crucial for determining the causal relationship between a specific variant in a gene and a disease, considering the inheritance pattern.

It is essential to specify not only the variant but also the gene name (preferably standardized like HUGO or RSC) when classifying variants as pathogenic for a particular phenotype.

Complexity of Genetic Variants

Some genes can be associated with multiple diseases or different inheritance patterns; thus, understanding these complexities is vital for accurate classification.

For instance, a gene may have both recessive and dominant mutations leading to similar diseases, necessitating precise nomenclature in reporting.

Clinical Context and Variant Interpretation

When classifying variants, it’s important to indicate that they are pathogenic for specific diseases rather than broadly associating them with all known conditions linked to that gene.

There are instances where a variant may be classified as pathogenic for one condition while being uncertain (VUS - Variant of Uncertain Significance) for another condition related to the same gene.

Distinction Between Classification and Clinical Relevance

The clinical presentation of patients can aid in variant classification but does not change its inherent classification status; each variant should theoretically apply universally across individuals.

A pathogenic variant might not manifest clinically in every individual due to factors such as heterozygosity or other genetic influences.

Reporting Standards in Genetic Testing

It’s critical to separate the classification process from individual patient assessments within reports. This ensures clarity on whether a variant is associated with an individual's clinical picture.

Reports should distinctly outline both the classification of variants concerning specific diseases and their relevance (or lack thereof) to individual cases.

Example Structure of Genetic Test Reports

An example report structure includes identification fields such as patient name, birth date, anonymized identifiers, biological sex (important for sample integrity), and test details.

Understanding Genetic Testing Results

Initial Identifications in Test Reports

The initial section of a test report typically includes patient identification details, sample information, and the specific test conducted. This part is generally consistent across laboratories.

Result Presentation and Interpretation

Results are highlighted for clarity; for instance, negative results may be presented with extensive commentary to explain findings.

In a case involving autism and suspected 22q11.21 deletion, no pathogenic or likely pathogenic variants were identified through whole exome sequencing.

Specific Findings Related to Clinical Suspicion

The absence of relevant genetic variants was noted concerning the patient's autism diagnosis, emphasizing the need for thorough investigation.

Separate analysis of mitochondrial DNA also yielded no significant findings, although combining nuclear genes and mitochondrial data is an option based on laboratory preferences.

Detailed Reporting on Copy Number Variants (CNVs)

A third result indicated that no copy number variations were detected related to the clinical presentation; however, specific mention was made regarding the suspicion of 22q11.21 deletion.

Tailoring reports to address specific clinical suspicions enhances communication with requesting physicians about what has been investigated.

Conclusion and Technical Details

Negative results simplify interpretation by confirming that no pathogenic variants correlate with the patient's clinical condition.

Comments accompanying reports often provide context for any identified pathogenic variants when present; in this case, comments focused on negative findings.

Quality Assurance in Genetic Testing

Detailed technical descriptions are essential in reports, including specifics about sequencing methods used (e.g., capture kits, sequencers).

Quality metrics such as coverage percentages at different thresholds (10x and 20x) are crucial for ensuring reliable variant detection.

Limitations of CNV Analysis

Clinical Insights on Autism Testing

Overview of Variant Classification in Autism Testing

The classification of genetic variants related to autism is based on ACMG criteria, utilizing databases like ClinVar and HGMD for reference.

Tools such as Ravel, SpliceAI, and Mutation Taster are essential for analyzing variants; benign or likely benign variants may not be reported if unrelated to the clinical picture.

Reporting Variants and Patient Choices

In cases where no pathogenic variants are identified, patients can choose whether to report secondary findings according to ACMG guidelines.

A negative exome result suggests a potential multifactorial etiology for autism, given that 80% of autism cases have a genetic component.

Limitations of Exome Testing

The exome test does not effectively identify common variants contributing to polygenic inheritance due to its focus on rare monogenic conditions.

Common low-impact variants may not be classified as pathogenic under current literature standards, leading them to be categorized as benign or VUS (variants of uncertain significance).

Understanding the Nature of Autism Variants

Only 20-25% of autism cases are attributed to rare variants; thus, VUS will only be included if they fall within specific categories defined by SFARI.

Reanalysis of exonic variants after two years could yield new insights into previously unreported findings.

Documentation and Reporting Standards

Comprehensive references should accompany reports; including extensive gene lists ensures thorough evaluation while maintaining clarity in documentation.

Reports should prioritize conciseness with critical information presented on the first page; detailed limitations and references can follow.

Case Study: Positive Findings in Exome Sequencing

A complete exome sequencing revealed a likely pathogenic variant associated with mitochondrial metabolism issues in a patient.

Genetic Variant Classification and Interpretation

Overview of Pathogenic Variant Classification

A pathogenic variant must be classified according to a specific disease and inheritance pattern. To maintain conciseness in results, detailed comments are often included separately.

Clinical Interpretation of Variants

The interpretation indicates that the patient's clinical presentation is likely due to the described variant in a specific gene, identified in homozygous state as probably pathogenic for mitochondrial DNA syndrome with autosomal recessive inheritance.

Importance of Data Presentation

When describing variants from NGS sequencing, it is recommended to use tables for quick visualization. Key information includes gene name, HGVS nomenclature, chromosomal location, and exon details.

Coverage and Allelic Fraction Analysis

It is crucial to report the altered allele fraction and coverage at the position of interest. For instance, a coverage of 158x with all bases read as alternate provides strong confidence in variant quality.

Assessing Quality of Variants

If 100% of reads show an alternate allele at high coverage (e.g., 158x), this confirms homozygosity. Conversely, low allelic fractions (e.g., 15%) may indicate false positives or issues like pseudogenes or systematic errors in sequencing.

Population Frequency Considerations

Including allelic frequency data from relevant populations (especially Brazilian populations for local patients) is essential for assessing pathogenicity criteria.

Genetic Counseling Recommendations

Genetic counseling should be indicated post-testing by qualified health professionals. This ensures proper understanding and implications of test results.

CNV Findings Reporting

Negative findings for copy number variations (CNVs) were reported separately to emphasize the significance of the identified pathogenic variant without complicating the main result section.

Criteria for Pathogenicity Classification

The classification as probably pathogenic relies on several criteria: rarity in population databases, detection in affected individuals, presence in mutation hotspots, and previous reports supporting its pathogenic nature.

Comprehensive Reporting Structure

The complete report spans two pages: one page contains essential information while the second elaborates on limitations and detailed descriptions related to variants analyzed.

Conclusion on Reporting Standards

Clinical Interpretation of Genetic Variants

Importance of Clinical Interpretation in Genetic Testing

The interpretation of genetic variants should specify the associated phenotype and inheritance pattern, rather than simply labeling a variant as "likely pathogenic."

Healthcare professionals can access segregation data to enhance clinical context, potentially reclassifying a variant from VUS (Variant of Uncertain Significance) to pathogenic based on specific clinical presentations.

Clinical interpretation must consider family history and other relevant clinical data; genetic counseling is essential for all genetic findings due to potential implications for family members.

While the final clinical interpretation rests with the requesting physician, laboratories should provide insights on whether they believe there is an association between the variant and disease in the patient.