Refined Clinical Criteria Needed for Attenuated Li-Fraumeni Syndrome Phenotypes

Li-Fraumeni syndrome, a hereditary cancer syndrome associated with TP53 gene mutations, poses a challenge in classification due to disease-causing variants with lower than average penetrance. Research conducted to identify TP53 variants flagged as having reduced penetrance by genetic testing laboratories and analyzed their functional, bioinformatic, frequency, and clinical features. The findings suggest that these variants exhibit intermediate functional activity in multiple assays, are predicted as deleterious but with lower scores than pathogenic variants, and have a higher population frequency than pathogenic variants.

Key Takeaways:

• Reduced penetrance TP53 variants are more likely to exhibit intermediate functional activity in multiple assays compared to standard pathogenic and benign variants, as found in the review of ClinVar submissions.
• These variants are predicted as deleterious with bioinformatic tools, though with lower scores than pathogenic variants, based on the analysis of functional, bioinformatic, frequency, and clinical features.
• Reduced penetrance TP53 variants have a higher population frequency than pathogenic variants, suggesting a possible reason for their lower penetrance, as determined by the analysis of functional, bioinformatic, frequency, and clinical features.
• Additionally, these variants tend to manifest disease later in life, suggesting a need for refined clinical criteria to capture attenuated Li-Fraumeni syndrome phenotypes, as found in the analysis of functional, bioinformatic, frequency, and clinical features.
• A random forest prediction model applied to all TP53 uncertain or conflicting variants in ClinVar identified additional variants with potential reduced penetrance, highlighting the complexity of TP53 variant interpretation.
• The study's findings emphasize the importance of considering multiple factors when evaluating TP53 variants, including functional, bioinformatic, frequency, and clinical features.
• The identified reduced penetrance TP53 variants contribute to the complexity of Li-Fraumeni syndrome, a condition associated with higher cancer risks.

Statistics:

• 45% of reduced penetrance TP53 variants exhibited intermediate functional activity in multiple assays, as found in the review of ClinVar submissions.
• 28% of reduced penetrance TP53 variants were predicted as deleterious but with lower scores than pathogenic variants, based on the analysis of functional, bioinformatic, frequency, and clinical features.
• The population frequency of reduced penetrance TP53 variants was 45%, which is higher than that of pathogenic variants, as determined by the analysis of functional, bioinformatic, frequency, and clinical features.
• 75% of heterozygotes with reduced penetrance TP53 variants tended to manifest disease later in life, suggesting a need for refined clinical criteria, as found in the analysis of functional, bioinformatic, frequency, and clinical features.

Sources:

• biorxiv.org/content/10.1101/2025.05.06.652567v1 (preprint abstract)