Beckwith-wiedemann Syndrome and Hemihyperplasia

BeckwithWiedemann syndrome, characterized by the triad of omphalocele, macroglossia, and gigantism, has a population incidence estimated at 1/13,700. This is likely an underestimate, because individuals with milder phenotypes may not be diagnosed. Some cases of isolated hemihyperplasia may, in fact, represent BeckwithWiedemann syndrome with reduced expressivity. Additional clinical features of BeckwithWiedemann syndrome include hemihyperplasia, umbilical hernia, diastasis recti, embryonal tumors, cytomegaly of the fetal adrenal cortex, ear anomalies, visceromegaly, renal abnormalities, and neonatal hypoglycemia. Supportivefindings may include polyhydramnios and prematurity, enlarged placenta, cardiomegaly, and characteristic facies. The latter feature is much more recognizable in early life and becomes less obvious over time. BeckwithWiedemann syndrome is a complex multigenic disorder caused by a variety of genomic and epigenomic alterations affecting the expression of growth regulatory genes on chromosome 1 lp l5 .