IQCJ (IQ motif containing J) encodes a calmodulin-binding protein that functions in neuronal signaling and lipid metabolism. The gene produces multiple transcript isoforms, including IQCJ-SCHIP1, a fusion transcript spanning two genes that encodes a protein highly expressed in brain tissue and localized to cytoplasm, actin-rich regions, and neurite extensions 1. The IQCJ-SCHIP1 protein functions as a late component of axon initial segments and nodes of Ranvier, binding calmodulin in a calcium-independent manner and interacting with ankyrin G and βIV-spectrin to stabilize multimolecular complexes essential for saltatory conduction 2. Loss-of-function mutations in SCHIP1/IQCJ-SCHIP1 cause severe neurodevelopmental disorders characterized by global developmental delay, brain malformations including anterior commissure agenesis, and polymicrogyria-cobblestone complex 3. Beyond its neurological functions, IQCJ variants influence plasma triglyceride levels and response to omega-3 fatty acid supplementation through gene-diet interactions and DNA methylation effects 45. The gene also shows sex-specific associations with late-life memory performance 6 and has been implicated in fatty liver development and lipid homeostasis regulation 78.