🎙️ Episode 65: Uncovering Hidden Splice Defects — Genome Sequencing and Group-Enrichment in Marfan Syndrome

🧬 In this episode of Base por Base, we delve into a groundbreaking study by Walker et al. (2025) in Genetics in Medicine that leverages whole-genome sequencing from the 100,000 Genomes Project alongside advanced in silico prediction and targeted RNA assays to reveal the contribution of non-canonical FBN1 splice variants to undiagnosed Marfan syndrome.

🔍 Key Highlights of the Study:
The authors systematically screened over 78,000 genomes, identifying 20 ultra-rare FBN1 variants in 23 families that lie beyond the ±8-base canonical splice regions; enrichment analysis showed these deep intronic and pseudoexon-creating variants account for approximately 3% of Familial Thoracic Aortic Aneurysm Disease cases previously lacking a molecular diagnosis; 70% of the variants were predicted to generate novel pseudoexons or extend exons, often introducing premature termination codons; experimental confirmation via RT-PCR, minigene constructs, and limited RNA-seq validated splicing aberrations for 16 of the 20 variants; replication in UK Biobank participants coded for Marfan syndrome supported a significant enrichment of predicted splice defects; these findings underscore the power of integrating genome sequencing, SpliceAI predictions, and bespoke RNA testing to uncover cryptic splice mutations that standard clinical assays may miss .

🧠 Conclusion:
This work inaugurates a new paradigm in Marfan diagnostics, demonstrating that systematic intronic analysis and confirmatory RNA assays can lift the veil on cryptic splice variants, thereby enhancing diagnostic yield and guiding more precise surveillance strategies for individuals at risk.

📖 Reference:
Walker S., Bunyan D.J., Thomas H.B., et al. (2025). Utility of genome sequencing and group-enrichment to support splice variant interpretation in Marfan syndrome. Genetics in Medicine. https://doi.org/10.1016/j.gim.2025.101477

📜 License:
This episode is based on a journal pre-proof published by Elsevier Inc. on behalf of the American College of Medical Genetics and Genomics. All rights reserved.