The etiological role of IGF2 in regulating intrauterine growth and tumour formation has been established in animal studies [14,15]; however its role in the other features of BWS (such as exomphalos, macroglossia, ear abnormalities, hemihyperplasia) and SRS (craniofacial abnormalities, clinodactyly, genital abnormalities) is unknown, but might relate to the wide range of tissues in which IGF2 is expressed. Here, IGF2 is linked to isolated hemihyperplasia.