To assess the role of left atrial cardiomyocyte PITX2 in recurrent AF, we quantified PITX2 mRNA in cardiomyocyte and non-cardiomyocyte nuclei from another set of 52 left atrial appendage samples using a pericentriolar material–1 (PCM1) cardiomyocyte enrichment protocol (Figure 3A) (20). The gene discussed is PITX2; the disease is atrial fibrillation.