POPDC2 and atrioventricular block: We performed a look-up of the p.Arg263Cys variant in recent whole-genome sequencing dataset29 consisting of young affected individuals (n = 226) receiving a pacemaker because of AV block, and none of the individuals was homozygous for p.Arg263Cys, nor were there any individuals with bi-allelic variants in POPDC2 (Note S2).