Presentation description

Atrial fibrillation (AF) is the most common cardiac arrhythmia and increases the risk of stroke and heart failure. It has a strong genetic component, but its molecular mechanisms remain unclear. We previously identified a mutation in a conserved region of the transcription factor NFATC1 in a family with young-onset AF, highlighting NFATC1 as a candidate gene for AF susceptibility. NFATC1 has 10 RNA curated splicing variants, but their expression level in the human heart or contribution to AF is unknown. We hypothesize that only a subset of NFATC1 variants is expressed in the heart, with some enriched in atrial tissue and potentially contributing to AF. We designed variant-specific primers and optimized them in induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) using a combination of PCR, gel electrophoresis, and sequencing. Due to high sequence similarity, some primers targeted multiple variants. We then tested the primers in human tissue (3 atria, 3 ventricles) and found that variant 10 is expressed highly in ventricles when compared to atria (intensity 10092±53vs.5775±46), suggesting region- or chamber-specific expression. Other primer sets showed no bands in heart tissue despite expression in iPSCs, indicating some variants may be absent or lowly expressed in the human heart. Future work will focus on increasing the sample number, quantifying transcript levels via qPCR, and using restriction enzymes to distinguish between highly similar variants. Characterizing NFATC1 transcript expression will help define which variants are present in the heart and may contribute to AF, potentially identifying new targets for precision therapies.