Supplementary Material for: Beckwith-Wiedemann Syndrome: Growth Pattern and Tumor Risk according to Molecular Mechanism, and Guidelines for Tumor Surveillance

<b><i>Background:</i></b> Beckwith-Wiedemann syndrome (BWS) is an overgrowth syndrome associated with an increased risk of pediatric tumors. The underlying molecular abnormalities may be genetic (<i>CDKN1C</i> mutations or 11p15 paternal uniparental isodisomy, pUPD) or epigenetic (imprinting center region 1, ICR1, gain of methylation, ICR1 GOM, or ICR2 loss of methylation, ICR2 LOM). <b><i>Aim:</i></b> We aimed to describe a cohort of 407 BWS patients with molecular defects of the 11p15 domain followed prospectively after molecular diagnosis. <b><i>Results:</i></b> Birth weight and length were significantly higher in patients with ICR1 GOM than in the other groups. ICR2 LOM and <i>CDKN1C</i> mutations were associated with a higher prevalence of exomphalos. Mean adult height (regardless of molecular subtype, n = 35) was 1.8 ± 1.2 SDS, with 18 patients having a final height above +2 SDS. The prevalence of tumors was 8.6% in the whole population; 28.6 and 17.3% of the patients with ICR1 GOM (all Wilms tumors) and 11p15 pUPD, respectively, developed a tumor during infancy. Conversely, the prevalence of tumors in patients with ICR2 LOM and <i>CDKN1C</i> mutations were 3.1 and 8.8%, respectively, with no Wilms tumors. <b><i>Conclusion:</i></b> Based on these results for a large cohort, we formulated guidelines for the follow-up of these patients according to the molecular subtype of BWS.