A Novel Heterozygous Intronic Mutation in the Gene Contributes to RNA Missplicing Events in the Marfan Syndrome.

Marfan syndrome (MFS) is an autosomal dominantly inherited connective tissue disorder, mostly caused by mutations in the fibrillin-1 () gene. We, by using targeted next-generation sequence analysis, identified a novel intronic mutation (the c.2678-15C>A variant) in a MFS patient with aortic dilatation. The computational predictions showed that the heterozygous c.2678-15C>A intronic variant might influence the splicing process by differentially affecting canonical versus cryptic splice site utilization within intron 22 of the gene. RT-PCR and Western blot analyses, using minigenes transfected into HeLa and COS-7 cells, revealed that the c.2678-15C>A variant disrupts normal splicing of intron 22 leading to aberrant 13-nt intron 22 inclusion, frameshift, and premature termination codon. Collectively, the results strongly suggest that the c.2678-15C>A variant could lead to haploinsufficiency of the FBN1 functional protein and structural connective tissue fragility in MFS complicated by aorta dilation, a finding that further expands on the genetic basis of aortic pathology.