POPDC2 and chronic obstructive pulmonary disease: Similar to the cardiac arrhythmia phenotype observed in mice, popdc1 and popdc2 zebrafish morphants and the popdc1S191F KI mutant also presented a cardiac arrhythmia phenotype, albeit in form of an AV-block as opposed to the stress-induced sinus bradycardia that was recorded in mice [29,101].