CPLANE1 (ciliogenesis and planar polarity effector complex subunit 1) is a core component of the CPLANE complex essential for ciliogenesis and cellular polarity establishment 12. The protein functions in recruiting peripheral IFT-A proteins to basal bodies and regulating ciliary transition zone assembly, processes critical for primary cilium formation and function. CPLANE1 operates as part of a larger protein complex coordinating both ciliary structure and planar cell polarity signaling, thereby supporting directional cell migration and proper neuronal development 3. Pathogenic variants in CPLANE1 cause Joubert syndrome 17 and orofaciodigital syndrome 6, both ciliopathies characterized by neurodevelopmental defects. CPLANE1 mutations are among the most common genetic causes of Joubert syndrome, with the molar tooth sign (characteristic cerebellar-brainstem malformation) and multi-systemic complications including ocular, hepatic, and renal involvement 4. Clinically, CPLANE1-related disease presents with hypotonia, psychomotor delay, and intellectual disability. Novel variants identified include frameshift mutations, intronic splice-disrupting variants, and intragenic duplications, many demonstrating pathogenicity through nonsense-mediated mRNA decay mechanisms 56. The high incidence of CPLANE1 mutations in early pregnancy losses suggests critical developmental importance 7. Patient-derived iPSC models confirm that CPLANE1 mutations impair neuronal differentiation and produce ciliary defects 3.