 For example, a point mutation in FGFR3 can lead to achondroplasia.The fibroblast growth factor receptors consist of an extracellular ligand domain composed of three immunoglobulin-like domains, a single transmembrane helix domain, and an intracellular domain with tyrosine kinase activity.These receptors bind fibroblast growth factors, members of the largest family of growth factor ligands, comprising 22 members.