Interestingly, in a knockout mouse model, deletion of the gene transcript for placenta specific expression of Igf2 results in the reduction of placental growth while fetal growth is maintained in association with an up-regulation of glucose transporter (GLUT3) and amino acid transporter (SNAT2) during mid gestation, however IUGR still develops near term [59,60,61]. This evidence concerns the gene SLC38A2 and fetal growth restriction.