Human neuronal networks on micro-electrode arrays as a tool to assess genotype-phenotype correlation in CACNA1A-related disorders.

CACNA1A-related disorders constitute a diverse group of neurological conditions, including ataxia, migraine, and epilepsy. Despite extensive genetic studies, clear genotype-phenotype correlations remain elusive. Moreover, next-generation sequencing has identified many variants of uncertain significance (VUS). Here, we leveraged patient-derived and CRISPR-Cas9-engineered human neuronal networks to explore relationships between CACNA1A variants and neurophysiological activity. CACNA1A haploinsufficiency induced subtle alterations in glutamatergic network activity, whereas missense variants had a more pronounced effect on overall network function. Network fingerprints were most affected from patients where ataxia co-occurred with migraine or epilepsy. Furthermore, we analyzed the impact of CRISPR-Cas9-induced VUS on network developmental trajectories. Although functional changes could not be directly linked to clinical phenotypes, all tested variants induced measurable alterations in neuronal network function, supporting their classification as likely pathogenic. These findings highlight the potential of human neuronal networks as a translational model for evaluating CACNA1A variant effects and improving clinical variant interpretation.