Beckwith-Wiedemann syndrome (BWS) is a human genomic imprinting disorder that presents with a wide spectrum of clinical features including overgrowth, abdominal wall defects, macroglossia, neonatal hypoglycemia, and predisposition to embryonal tumors. It is associated with genetic and epigenetic changes on the chromosome 11p15 region, which includes two imprinting control regions. Here we review strategies for diagnosing and managing BWS and delineate commonly used genetic tests to establish a molecular diagnosis of BWS. Recommended first-line testing assesses DNA methylation and copy number variation of the BWS region. Tissue mosaicism can occur in patients with BWS, posing a challenge for genetic testing, and a negative test result does not exclude a diagnosis of BWS. Further testing should analyze additional tissue samples or employ techniques with higher diagnostic yield. Identifying the BWS molecular subtype is valuable for coordinating patient care because of the (epi)genotype-phenotype correlations, including different risks and types of embryonal tumors.

Beckwith‐Wiedemann syndrome (BWS) is the most common epigenetic overgrowth and cancer predisposition disorder. Due to both varying molecular defects involving chromosome 11p15 and tissue mosaicism, patients can present with a variety of clinical features, leading to the newly defined Beckwith‐Wiedemann spectrum (BWSp). The BWSp can be further divided into three subsets of patients: those presenting with classic features, those presenting with isolated lateralized overgrowth (ILO) and those not fitting into the previous two categories, termed atypical BWSp. Previous reports of patients with BWS have focused on those with the more recognizable, classic features, and limited information is available on those who fit into the atypical and ILO categories. Here, we present the first cohort of patients recruited across the entire BWSp, describe clinical features and molecular diagnostic characteristics, and provide insight into practical diagnosis and management recommendations that we have gained from this cohort.

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Background: Macroglossia, a cardinal feature of the (epi)genetic disorder Beckwith-Wiedemann syndrome, is associated with obstructive sleep apnea, speech and/or feeding difficulties, and dental or jaw malalignment. These sequelae may be treated and/or prevented with tongue reduction surgery; the authors sought to determine whether certain Beckwith-Wiedemann syndrome patients may benefit from early surgical intervention before age 12 months. Methods: The authors conducted a retrospective review of patients with Beckwith-Wiedemann syndrome who underwent tongue reduction from 2014 to 2019. The authors assessed primary outcomes of change in obstructive sleep apnea by polysomnography, respiratory support required, and feeding route before and after tongue reduction, and reviewed postoperative complications and the need for repeated tongue reduction. Results: Of the 36 patients included, the median age at tongue reduction was 9.5 months (interquartile range, 3.8 to 22.8 months). For those with severe obstructive sleep apnea, there was a significant reduction in the obstructive apnea hypopnea index from 30.9 ± 21.8 per hour to 10.0 ± 18.3 per hour (p =0.019) and improvement in nadir oxyhemoglobin saturation from 72 ± 10 percent to 83 ± 6 percent (p =0.008). Although there was no significant change in overall supplemental feeding tube or respiratory support, there were specific patients who experienced clinically meaningful improvement. Of note, these positive outcomes applied equally to those who underwent surgery at a younger age (<12 months). To date, only one patient required a repeated tongue reduction. Conclusion: Based on improved polysomnographic findings and rarity of surgical complications or repeated surgery, the authors’ data support the safety and efficacy of this early intervention when clinical indications are present and an experienced multidisciplinary team is available for consultation. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.