Genome Sequencing Readily Detects a Copy Number Variant in FBN1 in a Patient with Marfan Syndrome

Marfan syndrome is characterized by musculoskeletal, ocular, and cardiovascular findings and results from heterozygous disease-causing variants in FBN1 (fibrillin-1). Given that the majority of pathogenic variants in FBN1 are single-nucleotide variants (SNVs) or variants smaller than 50 base pairs, routine clinical genetic testing is optimized for these variant types. Here, we present an individual with a clinical diagnosis of Marfan syndrome, in whom routine commercial testing was nondiagnostic.