FBN1 and Marfan syndrome: In our cohort, 5 out of 62 patients (8.1%) with diagnosed or suspected MFS but with negative results in panel sequencing had large FBN1 deletions, which proved it to be efficacious and cost-effective to screen for FBN1 large genomic rearrangement in those MFS patients with multiple systemic involvements and a negative FBN1 sequencing result.