This heterogeneous condition was finally named as Laron Syndrome or primary Growth Hormone insensitivity (GHI), and it includes: GH receptor deficiency (the most common), GH-GH receptor signal transduction defect, IGF-I synthetic defect, IGF-I receptor deficiency and IGF-I/IGF-I receptor signal transduction defects. This evidence concerns the gene IGF1R and Laron syndrome.