Multiplexed Functional Mapping of CACNA1C Disease Variants in hiPSC-Derived Neurons

About This Grant

ABSTRACT A major challenge in clinical genomics is the interpretation of variants of uncertain significance (VUS), which comprise the majority of disease-associated mutations cataloged in human genetic databases. This limitation is especially acute in neuropsychiatric and neurodevelopmental disorders, where cellular context and gene function are tightly intertwined. CACNA1C, which encodes the L-type calcium channel Cav1.2, exemplifies this challenge: common variants are strongly associated with psychiatric disorders such as schizophrenia and bipolar disorder, while rare mutations cause severe developmental syndromes like Timothy Syndrome. To address the need for scalable, physiologically relevant functional annotation, we propose to develop a next-generation neural multiplexed assay of variant effect (MAVE) platform that combines prime editing with a calcium-activity–based phenotyping system in human neurons. Using ~2,000 CACNA1C variants as a test case, we will integrate precision genome editing with a novel biochemical calcium recorder (CaST) in hiPSC-derived neurons to assess variant impact on calcium signaling. This approach enables classification of variants into gain-, loss-, or benign- function categories in a scalable and context-specific manner. By overcoming limitations of existing MAVEs in fidelity, scalability, and neuronal relevance, this platform will accelerate variant interpretation, enable therapeutic prioritization, and be broadly extensible to other calcium channel genes and functional modalities.