Conversely, knockdown of Cyp6a20 in cone cells with the pros-GAL4 driver completely abolished LMD behavior without affecting CL (Fig. 5f and g), indicating that Cyp6a20 functions in a specific subset of cone cells, similar to CrzR, to regulate LMD behavior (Fig. 4d). The gene discussed is PROS1; the disease is Langer mesomelic dysplasia.