CFAP126 (cilia and flagella associated protein 126), also known as Flattop, is a microtubule inner protein component of dynein-decorated doublet microtubules in the ciliary axoneme 1. Primary functions include regulating basal body docking and positioning in multiciliated cells, cilia formation in lung cells, and kinocilium positioning in the inner ear 1. Beyond ciliary biology, CFAP126 serves as a Wnt/planar cell polarity (PCP) pathway effector and marker gene distinguishing proliferation-competent from mature pancreatic β-cells, with its expression increasing during 3D islet maturation 2. The gene can be monitored in human models using CRISPR-engineered reporter iPSC lines to track Wnt/PCP signaling during endocrine development 3. Clinically, CFAP126 mutations have been identified as potential biomarkers in focal cortical dysplasia-related drug-resistant epilepsy 4. A heterozygous nonsense mutation (c.310A>T, p.Lys104*) in CFAP126 has been associated with a novel familial diabetes phenotype responsive to oral sulfonylureas, suggesting the gene's critical role in insulin secretion regulation 5. These findings indicate CFAP126 functions at the intersection of ciliary organization and endocrine cell biology, with implications for neurological and metabolic disease.