Beckwith-Wiedemann syndrome was excluded through sequencing and methylation studies of CDKN1C, KvDMR1, H19DMR, and UDP11, and no mutations were identified on sequencing AKT2. NGS of the family trio identified no high probability, de novo, potentially function-altering variants nor any plausibly disease-causing homozygous variants, while rare, plausibly functional compound heterozygous variants (CADD score c.21 for both variants) were found only in TTN, encoding the extremely large cytoskeletal Titan protein. Here, TTN is linked to Beckwith-Wiedemann syndrome.