POC5 is a centriolar protein essential for centriole assembly and elongation 12. It functions as a negative regulator of centriole elongation 3 and acts as a core component of the inner centriolar scaffold, where it forms tetramers and interacts with POC1A to maintain centriole structural integrity 4. POC5 is critical for cilia formation and cell cycle progression 5. At the molecular level, POC5 localizes to the centriole lumen and is stabilized through protein-protein interactions with other scaffold components. The gene is estrogen-responsive in osteoblasts, regulated via estrogen receptor ERα binding to an estrogen response element in the POC5 promoter 5. Additionally, POC5 is protected from proteasomal degradation through the HDAC3-KDELR2 axis, linking its stability to cell cycle progression in cancer cells 6. Clinically, bi-allelic loss-of-function POC5 variants cause a syndromic ciliopathy characterized by rod-cone dystrophy, insulin-resistant diabetes mellitus, partial lipodystrophy, kidney disease, and muscle dysfunction 7. POC5 mutations are associated with adolescent idiopathic scoliosis with sex-specific estrogen-dependent effects 5. POC5 variants also correlate with metabolic traits including BMI and respiratory disease susceptibility 89, and rare fusions involving POC5 have been identified in head and neck carcinomas 10.