Base editing in the AUTS2 gene and high-throughput NGS genotyping of clones: a strategy for generating a cellular...

Studying the molecular mechanisms underlying autism spectrum disorders (ASD) requires cellular models capable of capturing cis-regulatory effects and allele-specific gene expression. In this study, we present an approach for generating induced pluripotent stem cells (iPSCs) modified using an adenine base editor (ABE) to introduce synonymous single-nucleotide substitutions in the AUTS2 gene - a candidate involved in ASD pathogenesis. These substitutions serve as allele-specific markers, enabling the tracking of expression differences between normal and rearranged alleles in a cis-regulatory context. We developed a high-efficiency strategy for genotyping clones using amplicon-based next-generation sequencing (NGS). Analysis of over 100 subclones demonstrated that this approach surpasses Sanger sequencing in scalability, sensitivity, and cost-effectiveness. We selected clones with targeted heterozygous substitutions, assessed mosaicism levels, and performed phasing with germline heterozygous variants to confirm monoclonal origin and identify the allele carrying the chromosomal rearrangement. The resulting iPSC lines mark distinct AUTS2 alleles, providing a foundation for analyzing the impact of cis-regulatory elements on gene expression across different cell types. Our findings highlight the practical value of base editors and targeted NGS genotyping in creating cellular models with single-nucleotide substitutions for both basic and applied research.