日本小児循環器学会雑誌 Pediatric Cardiology and Cardiac Surgery

FBN1 mutations causing severe and early-onset Marfan syndrome (MFS) cluster in exons 24–32. Here, we report the case of a male patient with early-onset MFS who was born with arachnodactyly, annuloaortic ectasia (AAE), and aortic regurgitation (AR). At 4 years of age, he presented with progressive AAE and severe AR and was referred to our hospital. He immediately underwent David procedure. The DNA sequencing of FBN1 identified a previously reported de novo mutation in the splicing donor site of intron 29 [IVS29＋1G＞A], and transcript analyses revealed that this mutation had mediated an in-frame skipping of exon 29. Currently, the pathogenic mechanisms underlying MFS are classified as dominant-negative effect or haploinsufficiency of FBN1. However, splicing mutations can be associated with both mechanisms and require qualitative and quantitative analyses of the gene products. The severe aortic phenotype in our case appeared to be affected by the “location” (FBN1 exon 29) and the “type” of mutation (splicing mutation).