The IGF1R gene consists of 26 exons and it encodes a transmembrane protein called insulin-like growth factor 1 receptor (IGF1 receptor). IGF1 receptor binds to insulin-like growth factor 1 (IGF1) activating the PI3K-AKT/PKB pathway and the Ras-MAPK pathway that play a key role in the regulation of cell growth and cell survival. Variations in IGF1R gene are associated with IGF-I resistance and ring chromosome 15. IGF1R gene mutations are known to reduce the number of IGF1 receptors in affected individuals which can interfere with the normal functioning of the signalling pathways it is involved in. This results in intrauterine and postnatal growth retardation. Additionally, IGF1R gene is also implicated in several types of cancer.