A novel 'splice site' HCN4 Gene mutation, c.1737Â +Â 1 GÂ >Â T, causes familial bradycardia, reduced heart rate response, impaired chronotropic competence and increased short-term heart rate variability

The identified novel 'splice site' HCN4 gene mutation, c.1737 + 1 G > T, causes familial bradycardia and leads to reduced heart rate response, impaired chronotropic competence and increased short-term heart rate variability in the mutation carriers.