Silver-Russell syndrome ( is a clinically heterogeneous condition characterized by severe intrauterine growth retardation, poor postnatal growth, craniofacial features such as a triangular shaped face and a broad forehead, body asymmetry, and a variety of minor malformations. The phenotypic expression changes during childhood and adolescence, with the facial features and asymmetry usually becoming more subtle with age. Hypomethylation at distal chromosome 11p15 (ICR1) represents a major cause of the disorder. Opposite epimutations, namely hypermethylation at the same region on 11p15, are observed in about 5 to 10% of patients with Beckwith-Wiedemann syndrome (BWS; 130650), an overgrowth syndrome (Bartholdi et al., 2009).