FGFR3 is one of 4 high affinity tyrosine kinase receptors for the fibroblast growth factor family of ligands. On ligand stimulation, FGFR3 undergoes dimerization and tyrosine autophosphorylation, resulting in cell proliferation or differentiation, depending on the cell context, through the mitogen-activated protein kinase (MAPK) and phospholipase Cγ signal transduction pathways. All known mutations are believed to result in ligand-independent activation of the receptor. Germ line mutations in this gene lead to craniosynostosis and multiple types of skeletal dysplasia. However, somatic mutations of FGFR3 gene are very rare in brain tumors. In some cases, the possibility of FGFR3 variants being germline can not be excluded. Clinical correlation is recommended.