Genetic Variant Reclassification in Cardiovascular Disease
Definition
Variant reclassification refers to the process of updating the pathogenicity classification of a previously reported genetic variant (per ACMG/AMP criteria: class 1–5) in light of new evidence. In cardiovascular genetics, reclassification is frequent — affecting over one-third of previously classified variants — and carries direct clinical consequences for probands and their families.
Key Concepts
Reclassification Rates
- Overall reclassification rate in inherited cardiovascular diseases: >36% (Fernandez-Falgueras et al. 2024). Comparable to rates in other rare disease domains: survivors of cardiac arrest (38%), pediatric epilepsy (36%), dilated cardiomyopathy (30%). (sources/arrhythmia-genetics-mgenetik-2025 — high)
- By disease category: cardiomyopathy variants 28%; cardiac channelopathies 38%. (sources/arrhythmia-genetics-mgenetik-2025 — high)
- The majority of reclassifications result in downgrading of pathogenicity — i.e., class 4/5 variants reclassified to class 3 (VUS) or lower — driven primarily by updates to population databases and reassessment against current ACMG criteria. (sources/arrhythmia-genetics-mgenetik-2025 — high)
- Per-variant annual reclassification rate: LP/P or likely benign variants reclassify at 1–8%/year, predominantly toward VUS; VUSs reclassify at even higher rates over time. (sources/incident-gene-aha-2023 — high)
- HCM-specific data: 11% of HCM variants reclassified over 6 years (AHA 2024). Class I recommendation to re-evaluate every 2–3 years. (sources/HCM-AHA-2024 — high)
Drivers of Reclassification
- Additional affected cases and variant co-segregation data in extended families
- Experimental loss-of-function or gain-of-function evidence
- Other functional data (iPSC-CM studies, electrophysiology assays)
- Updated population allele frequency databases (gnomAD, ClinVar, LOVD)
- Publication of novel disease gene associations and updated ClinGen curations
- Time interval since initial classification (sources/arrhythmia-genetics-mgenetik-2025 — high)
Clinical Consequences
- Downgrading: a family that was told a variant was pathogenic may have members unnecessarily surveilled or treated; cascade testing results may need to be reconsidered.
- Upgrading: relatives who were told they were "gene-negative" based on a previously classified VUS may actually carry a pathogenic variant and require surveillance.
- No standardized clinical infrastructure currently exists to systematically notify variant carriers when reclassification occurs. (sources/HCM-AHA-2024 — high)
HFSA 2018 — VUS Clinical Management in Cardiomyopathy
- VUS identified in the proband cannot be used for predictive cascade genetic testing in family members (sources/genetic-cmp-jcf-2018 — very high)
- Segregation analysis — tracking whether a VUS co-segregates with the cardiomyopathy phenotype across multiple affected family members — is the most powerful mechanism for reclassifying a VUS to LP/P (sources/genetic-cmp-jcf-2018 — very high)
- Novel variants in well-established genes (e.g., MYBPC3, MYH7) will frequently be classified as VUS at first encounter: 30–35% of variants in MYH7/MYBPC3 were novel in one HCM study; in other HCM genes, 76% of variants were unique (sources/genetic-cmp-jcf-2018 — very high)
- When a previously P/LP variant is downgraded to VUS: genotype-negative family members must be recalled to surveillance (their "gene-negative" result is no longer reassuring), and genotype-positive relatives must be re-counselled that management rationale may have changed (sources/genetic-cmp-jcf-2018 — very high)
- Bilineal disease (pathogenic variants from both parents) and digenic inheritance complicate segregation analysis and must be considered when VUS fails to segregate cleanly (sources/genetic-cmp-jcf-2018 — very high)
Who Is Responsible
- Clinical geneticists in interdisciplinary cardiogenetic centres are the primary professionals responsible for re-interpretation and communication of reclassified variants. (sources/arrhythmia-genetics-mgenetik-2025 — high)
- Reclassification must be communicated to the requesting healthcare professional and to variant carriers/affected family members.
- Re-evaluation of initial genetic findings at regular intervals (every 2–3 years for HCM per AHA 2024) is a Class I recommendation. (sources/HCM-AHA-2024 — high)
Incidental Variants — Recommended Follow-Up Cadence
- For incidentally identified variants in CVD genes, optimal variant re-evaluation interval: every 1–3 years, paired with clinical follow-up; timing individualized to variant and patient (sources/incident-gene-aha-2023 — high)
- Each follow-up should: reinterpret the genetic variant per updated ClinVar/ClinGen/community consensus; repeat disease-specific clinical testing; re-evaluate personal and family history; integrate genetic and clinical findings
- This ongoing surveillance is needed even in phenotype-negative individuals carrying an LP/P variant — and should be established before broad ES/GS testing is initiated (sources/incident-gene-aha-2023 — high)
Contradictions / Open Questions
- Downgrading dominates — but no standard notification system exists: The most common reclassification direction is downgrading from pathogenic to VUS. Yet no standardized clinical pathway ensures that affected families are notified when this occurs, potentially leaving them managed under a now-incorrect genetic diagnosis. The responsibility falls on individual centres without regulatory or IT infrastructure to enforce it. (sources/arrhythmia-genetics-mgenetik-2025, sources/HCM-AHA-2024)
- Reclassification vs. clinical inertia: Even when a variant is downgraded, ICD decisions and management plans already made are difficult to reverse — especially if the patient has experienced an arrhythmic event. The temporal gap between initial classification and reclassification means early management decisions are always made under uncertainty. (sources/arrhythmia-genetics-mgenetik-2025)
Connections
- Related to concepts/Cardiogenetic-Centers
- Related to concepts/Cascade-Family-Screening
- Related to entities/Long-QT-Syndrome
- Related to entities/Brugada-Syndrome
- Related to entities/CPVT
- Related to entities/HCM
- Related to entities/DCM
- Related to concepts/Genetic-Testing-in-Cardiomyopathy
- Related to sources/genetic-cmp-jcf-2018
- Related to concepts/Incidental-Cardiovascular-Variants
- Related to sources/incident-gene-aha-2023