To better understand Fgfr2+ cell populations in the developing AF, we analyzed a previously published single-cell RNA sequencing (scRNA-seq) dataset of the developing frontal suture at E18.5, which included the paired osteogenic fronts of the frontal bones and intervening AF connective tissue (FaceBase dataset 1-4TT6; Holmes et al., 2020). The gene discussed is FGFR2; the disease is atrial fibrillation.