142: PALB2 ACMG/AMP Specifications

Richardson M et al., The American Journal of Human Genetics - An international HBOP Variant Curation Expert Panel developed PALB2-specific specifications of the 2015 ACMG/AMP variant-interpretation guidelines by tailoring, limiting, or removing existing codes and tested them on 39 pilot variants to improve ClinVar concordance and harmonize classification. Key terms: PALB2, ACMG/AMP, variant curation, HBOP VCEP, ClinVar.

Study Highlights:
The HBOP VCEP reviewed ACMG/AMP codes and advised against 13 codes, limited six, and tailored nine to PALB2-specific biology. They set conservative population thresholds (BA1 0.1%, BS1 0.01%) and refined PVS1/PVS1(RNA) application, defining Tyr1183 as a C-terminal boundary for loss-of-function evidence. A pilot curation of 39 variants produced concordant classifications for 31 of 37 ClinVar variants (84%) and led to reclassification of several VUS/conflicting entries. The recommendations are conservative and evidence-based to support harmonized PALB2 variant interpretation and clinical reporting.

Conclusion:
PALB2-specific ACMG/AMP specifications provide a conservative, evidence-based framework that improves harmonization and accuracy of variant classification, supporting ClinVar deposition and clinical management of carriers.

Music:
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Article title:
Specifications of the ACMG/AMP variant curation guidelines for the analysis of germline PALB2 sequence variants

First author:
Richardson M

Journal:
The American Journal of Human Genetics

DOI:
10.1016/j.ajhg.2025.08.020

Reference:
Richardson M.E. et al., Specifications of the ACMG/AMP variant curation guidelines for the analysis of germline PALB2 sequence variants. The American Journal of Human Genetics. 2025;112:1–15. https://doi.org/10.1016/j.ajhg.2025.08.020

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

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Episode link: https://basebybase.com/episodes/specifications-of-the-acmg-amp-guidelines-for-palb2-variant-interpretation

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2025-09-19.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the transcript sections on PALB2 biology, HBOPVCEP PALB2 specifications, ACMG/AMP code modifications, pilot study outcomes, missense/pathogenicity limitations, PVS1/Tyr1183 boundary, splicing guidance, VUS backlog, and the need for high-throughput functional assays.
- transcript topics: PALB2 role in homologous recombination repair; HBOPVCEP PALB2 specifications and code changes; Pilot study results and ClinVar concordance; VUS resolution outcomes; Missense pathogenicity limitations and splicing considerations; PVS1, Tyr1183 boundary and RNA splicing guidance

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 7
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- HBOPVCEP PALB2 specifications exist and tailor/limit ACMG/AMP codes for PALB2
- Pilot with 39 PALB2 variants; 37 in ClinVar; 84% concordance with ClinVar classifications
- Among ClinVar VUS/conflicts (14), 4 variants resolved to benign or LP/Pathogenic
- Missense pathogenicity not established; restricted use of several missense-driven codes
- BA1 0.1% and BS1 0.01% population thresholds; PM2_Supporting used for rarity
- PVS1 and PVS1(RNA) weighting; Tyr1183 boundary; splicing predictions guide PVS1/RNA and BP7/BP7(RNA)

QC result: Pass.