For example, deletion of the mouse orthologue of the human non-coding region that contains common AF-associated SNPs upstream of HCN4 (Roselli et al., 2018; Nielsen et al., 2018) severely downregulates Hcn4 in the SAN and alters the expression of the nearby genes, Loxl1, Nptn and Neo1 (van Ouwerkerk et al., 2020). Here, HCN4 is linked to atrial fibrillation.