SMO and Jeune syndrome: GRK2 deficiency leads to ATD through defects in ciliary signaling; GRK2 is a positive regulator of Hh signaling, and its absence leads to inhibition of GLI3 activity. inactivation of GRK2 leads to defects in cilia accumulation in SMO of chondrocytes as well as impaired Wnt signaling typical of GRK2-/- cells.