Insulin-like growth factor 2 and overgrowth: molecular biology and clinical implications

The insulin-like growth factors, IGF1 and IGF2, play a fundamental role in human fetal growth. Of the growth disorders that involve excessive growth, many could be attributable to overexpression of IGF2. Because one copy of the IGF2 gene is silenced by genomic imprinting, several different molecular errors can double the number of active copies of the IGF2 gene. Although not formally demonstrated, each of these errors is expected to double the level of IGF2 expression. The nature and severity of the overgrowth might be dependent on the number and location of cells that carry the molecular defect.