Schematic of a primary cilium. Primary cilia consist of an axoneme extending from the apical surface of cells and a basal body. Transition fibers connect the basal body to the plasma membrane. Primary cilia form from centrosomes when the mother centriole becomes the basal body while retaining its attachment to the daughter centriole. The transition zone is located between the axoneme and the basal body and contains Y-shaped linkages that connect the microtubules to the plasma membrane. The transition zone is important for regulating transport of molecules into and out of the cilium. IFT-A and IFT-B are polymeric complexes that cooperate with the molecular motors, kinesin, and dynein, to transport cilia molecules. The role of the BBSome is not well understood, but studies suggest it has some role in cilial trafficking. Analysis of HREM images from DMDD identifies pituitary hypoplasia in mice deficient in these genes. Patients have been identified who have mutations in these genes and exhibit ciliopathy phenotypes as well as hypopituitarism. This panel created using Biorender.com.
