CC2D2A encodes a component of the tectonic-like complex localized at the ciliary transition zone, functioning as a barrier that prevents diffusion of transmembrane proteins between cilia and plasma membranes. The protein is essential for primary cilia formation and sonic hedgehog signaling 1. CC2D2A mutations cause ciliopathies including Joubert syndrome-9, characterized by neurodevelopmental features such as the distinctive 'molar tooth sign' on brain MRI, developmental delay, hypotonia, and oculomotor dysfunction 12. Patient-derived iPSCs from CC2D2A mutation carriers show impaired differentiation into mid-hindbrain and cerebellar granule cells with notable ciliary defects compared to controls 3. CC2D2A-related Joubert syndrome typically presents with motor and language delay, though 74% of patients retain normal intellectual efficiency 2. The gene also associates with focal segmental glomerulosclerosis and nephronophthisis, indicating broader ciliary dysfunction in renal development 4. Additionally, CC2D2A polymorphisms show association with mental retardation susceptibility in Asian populations 5, and recent evidence suggests CC2D2A functions in mechanotransduction pathways relevant to idiopathic pulmonary fibrosis pathogenesis 6. Homozygous truncating variants predict more severe phenotypes 2.