Beckwith-Wiedemann syndrome with asymmetric mosaic of paternal disomy causing hemihyperplasia

Beckwith-Wiedemann syndrome (BWS) is a congenital disorder with 3 main features—overgrowth in infancy, macroglossia, and abdominal wall defects. Here, we report on a 5-month old girl with hemihyperplasia and macroglossia caused by paternal uniparental disomy (pUPD) asymmetric mosaic on chromosome 11p15.5. She could not retract her tongue into her mouth and the midline of the tongue was shifted to the left. Glossectomy was performed at age 1 year. A specimen of the tongue showed normal skeletal muscle, but the muscle fibers were closely spaced, and there were fewer stroma components in the tissue from the right side of the tongue than that from the left side. With respect to pUPD of chromosome 11p15.5, microsatellite marker analysis of the tongue tissue specimen revealed a higher mosaic rate in the tissue from the right side of the tongue (average 48.3%) than that from the left side (average 16.9%). Methylation analysis of Kv differentially methylated region (DMR) 1 (KvDMR1) and H19DMR revealed hypomethylation of KvDMR1 and hypermethylation of H19DMR in the tissue on the right side of the tongue (hyperplastic side). In this case, the difference in mosaic rate of pUPD in the 11p15.5 region was hypothesized to influence the expression level of insulin-like growth factor 2. This result may be helpful to clinicians, especially surgeons, when planning plastic surgery for hemihyperplasia.