CEP19 is a centrosomal and ciliary protein essential for cilia assembly and intraflagellar transport (IFT). Mechanistically, CEP19 recruits the activated GTP-bound RABL2 GTPase to the ciliary base, and the CEP19-RABL2 complex subsequently captures IFT complex B to trigger its entry into developing cilia 12. CEP19 also cooperates with FOP and CEP350 to recruit ciliary vesicles to the mother centriole's distal end, initiating cilium assembly 3. Additionally, CEP19 participates in microtubule anchoring at centrosomes and controls BBSome-mediated ciliary GPCR export through its role in the CEP19-RABL2-IFT-B axis 4. CEP19 mutations cause early-onset severe obesity and metabolic syndrome; homozygous null variants produce morbidly obese, hyperphagic, and insulin-resistant mice 5. Clinical presentations include severe obesity with diabetic ketoacidosis, metabolic syndrome, and variable ciliopathy features such as situs inversus abdominalis and polysplenia 6. These findings establish CEP19 as a critical ciliary protein whose dysfunction impairs ciliogenesis and metabolic regulation, implicating defective cilia assembly in monogenic obesity and ciliopathy phenotypes.