 In achondroplasia, the FGFR3 gene has a missense mutation at nucleotide 1138 resulting from either a G>A or G>C.This point mutation in the FGFR3 gene causes hydrogen bonds to form between two arginine side chains leading to ligand-independent stabilization of FGFR3 dimers.Overactivity of FGFR3 inhibits chondrocyte proliferation and restricts long bone length.