Trends in Blood Mosaicism and Clinical Phenotype Score in Patients with Beckwith-Wiedemann Syndrome Evaluated for Tongue Reduction Surgery.

INTRODUCTION: Most patients with Beckwith-Wiedemann syndrome (BWS) have macroglossia with some requiring tongue reduction surgery (TRS). This study reports correlations between levels of affected cells (mosaicism) and BWS clinical score in patients evaluated for TRS. We also show correlations of clinical score and mosaicism with obstructive sleep apnea (OSA) severity. METHODS: Blood mosaicism levels and BWS clinical score were recorded in patients with macroglossia referred to plastic surgery for evaluation. Associations among blood mosaicism, BWS clinical score, TRS, and OSA were assessed with appropriate statistics. RESULTS: Of the 225 patients included, BWS blood testing was available in 128 (56.9%). Mosaicism levels were higher in those who underwent TRS compared to those who did not (85.9 85.9 (56.5-95.9)% vs. 29.7 (2.8-73.1)%, p<0.001). BWS clinical score was also higher in those requiring TRS (9.0 (8.0-11.0) versus 7.0 (6.0-9.0), p<0.001). There was a positive correlation between clinical score and obstructive apnea-hypopnea index (r=0.320, p=0.011). Receiver operating characteristic curve analysis showed a clinical score ≥11 had 100% specificity and 36.4% sensitivity for detecting patients requiring TRS. Blood mosaicism ≥80% had 63.6% sensitivity and 83.6% specificity for predicting surgery. A combined criteria of BWS clinical score ≥11 or mosaicism ≥80% had 72.7% sensitivity and 83.6% specificity for predicting TRS. CONCLUSION: Blood mosaicism levels and higher BWS clinical scores appear associated with a greater frequency of having surgery in patients with macroglossia referred for surgical evaluation. Elevations in BWS clinical scoring are associated with increased OSA severity while increased blood mosaicism is not.

(Epi)genotype and Timing of Tongue Reduction Predict Safety and Long-Term Outcomes in Beckwith-Wiedemann Syndrome.

INTRODUCTION: Macroglossia is a cardinal feature of Beckwith-Wiedemann syndrome (BWS) with a clinical spectrum where the indication and timing for surgery remain to be validated. This study leverages a cohort of molecularly characterized patients with BWS to correlate epigenetic diagnosis with phenotype and treatment outcome. METHODS: Patients with BWS seen in consultation for macroglossia from 2009-2022 were reviewed for phenotype, molecular diagnosis, tongue reduction status, timing of surgery (early = under 12 months), and perioperative complications. RESULTS: Two hundred thirty-seven patients were included. Imprinting control region 2 loss of methylation (IC2 LOM) was the most common epigenotype (61%). Paternal uniparental isodisomy for chromosome 11 (pUPD11) comprised a larger proportion of patients undergoing tongue reduction (18%) than those not undergoing surgery (8%, p = 0.024) and was associated with need for repeat surgery (OR 4.49, 95% CI 1.06-18.98, p = 0.041). Complications including wound dehiscence, ventilator associated pneumonia, and unplanned extubation were more common in patients undergoing early surgery (20%) than late surgery (4%, OR 5.70, 95% CI 1.14-28.55, p = 0.034). CONCLUSIONS: This study presents one of the largest cohorts correlating molecular diagnosis with clinical course of macroglossia treatment in BWS. Macroglossia in patients with pUPD11 is associated with higher rates of reoperation. Relief of obstructive sleep apnea with early tongue reduction must be weighed against risk of perioperative complications, most of which are non-surgical. This study highlights how molecular diagnosis advances clinical care by risk stratifying clinical outcomes in a center providing integrated multidisciplinary care for the BWS population.

Occurrence of Hepatoblastomas in Patients with Beckwith-Wiedemann Spectrum (BWSp).

Patients with Beckwith-Wiedemann syndrome (BWS), an epigenetic imprinting disorder involving alterations in genes at the 11p15 chromosomal location, are predisposed to develop hepatoblastomas (HBs), which are rare embryonal liver tumors. Tumors can develop after a BWS diagnosis or, conversely, can be the presenting feature leading to a subsequent diagnosis. While HBs are the cardinal tumors of BWS, not all patients with the BWS spectrum will develop HBs. This observation has led to many hypotheses, including genotype-associated risk, tissue mosaicism, and tumor-specific second hits. To explore these hypotheses, we present the largest cohort of patients with BWS and HBs to date. Our cohort comprised 16 cases, and we broadened our sample size by searching the literature for all cases of BWS with HBs. From these isolated case studies, we amassed another 34 cases, bringing the total number to 50 cases of BWS-HB. We observed that paternal uniparental isodisomy (upd(11)pat) was the most common genotype, representing 38% of cases. The next most common genotype was IC2 LOM, representing 14% of cases. Five patients had clinical BWS without a molecular diagnosis. To investigate the potential mechanism of HBs in BWS, we analyzed normal liver and HB samples from eight cases and isolated tumor samples from another two cases. These samples underwent methylation testing, and 90% of our tumor samples underwent targeted cancer next-generation sequencing (NGS) panels. These matched samples provided novel insights into the oncogenesis of HBs in BWS. We found that 100% of the HBs that underwent NGS panel testing had variants in the CTNNB1 gene. We further identified three distinct groups of BWS-HB patients based on epigenotype. We also demonstrated epigenotype mosaicism, where 11p15 alterations can differ between the blood, HB, and normal liver. In light of this epigenotype mosaicism, tumor risk assessment based on blood profiling may not be accurate. Therefore, universal screening is recommended for all patients with BWS.