Multilocus Imprinting Disturbances (MLID) analysis in a cohort of 101 Beckwith-Wiedemann Syndrome patients

Abstract

Background: Beckwith-Wiedemann syndrome (BWS) is a genetic overgrowth disorder associated with DNA methylation anomalies in the 11p15.5 region, particularly affecting ICR1 and ICR2. These regions regulate key genes like IGF2 and CDKN1C, essential for growth and development. Multilocus imprinting disturbances (MLID) in BWS, are characterized by aberrant methylation in regions beyond 11p15.5 or other regions, are found in some BWS cases and are relevant for diagnosis and management. Material and Methods: The methylation status of 101 BWS patients was analyzed by both MS-MLPA and methylation microarrays. All selected patients had previously been diagnosed with BWS due to abnormal methylation in the 11p15.5 chromosomal region and compatible phenotype, using the SALSA MS-MLPA probemix ME030 BWS/RSS kit, while methylation microarrays (Infinium MethylationEPIC v2.0 BeadChip) provided genome-wide CpG site data, identifying additional methylation patterns. Raw data were processed in R and analyzed for differential methylation. Clinical feature differences were evaluated using statistical tests, including Chi-square and Fisher’s exact, with significance set at p<0.05. Results: ICR2 hypomethylation was prevalent in MLID cases (15.84% by MS-MLPA, rising to 26.73% using microarrays). Novel hypomethylated loci (DIRAS3, FAM50B, ZNF331) were detected, expanding the spectrum of epigenetic abnormalities in BWS. Significant loci like GNAS and PLAGL1 were frequently altered, consistent with previous reports. Conclusion: ICR2 hypomethylation is a diagnostic hallmark of MLID in BWS. Advanced methylation techniques improve diagnostic precision, revealing novel loci. These findings emphasize genome-wide approaches for comprehensive MLID analysis and suggest potential targets for future research and therapy development.