Beckwith-Wiedemann syndrome (BWS) is an overgrowth syndrome, characterized by macroglossia, macrosomia, hemihyperplasia, visceromegaly, embryonal tumors and abdominal wall defects and results from genetic and epigenetic disordered expression of imprinted genes at chromosome 11p15.5. Due to varying molecular defects, clinical presentation is heterogenous. Prematurity, macrosomia and high birth weight is common in patients with BWS. Herein, we investigated 25 patients with BWS and according to the underlying molecular etiology, patients were grouped into two as follows; Group 1: loss of methylation at IC2 (n:18); Group 2: gain of methylation at IC1 (n:2) and paternal uniparental disomy (UPD) (n:5). Groups were compared for birth weight, gestational week and presence of macrosomia. Differences between groups were not statistically significant. There are reports in the literature supporting that the genetic mechanism makes a difference in terms of these features. Our results are thought to support the view that the genetic mechanism is not the only determinant of these features.

Keywords: Beckwith-Wiedemann syndrome, DNA methylation, macrosomia, genotype and phenotype correlation