POPDC2 and atrioventricular block: In the study by Rinné et al.,35 a heterozygous nonsense variant in POPDC2 (p.Trp188Ter; rs144241265, allele frequency of 1.70 × 10−4 among European individuals in gnomAD12) was identified in the heterozygous state in a monozygotic twin pair presenting with AV block and in an unrelated family with a mother and son both diagnosed with first-degree AV block (i.e., prolongation of the PR-interval on the ECG).