FGFR3 is a member of the FGFR family of receptor tyrosine kinases. This family is known to regulate a host of cellular functions including angiogenesis, mitogenesis, osteogenesis, myogenesis, carcinogenesis, cellular differentiation, and tissue repair after injury. The FGFR family has also been implicated in a number of diseases including cancer, rheumatoid arthritis, and diabetic retinopathy. The K650E mutation leads to constitutive activation and the neonatal lethal disorder TDII.