- Bradycardia (HP:0001662): A slower than normal heart rate (in adults, slower than 60 beats per minute). Evidence: TAS. (OMIM:604559)
- Shortened PR interval (HP:0005165): Reduced time for the PR interval (beginning of the P wave to the beginning of the QRS complex). In adults, normal values are 120 to 200 ms long. Evidence: TAS. (OMIM:604559)
- Left anterior fascicular block (HP:0011711): Conduction block in the anterior division of the left bundle branch of the bundle of His. Evidence: TAS. (OMIM:604559)
- Prolonged QT interval (HP:0001657): Increased time between the start of the Q wave and the end of the T wave as measured by the electrocardiogram (EKG). Evidence: PCS. Frequency: 6/71. (PMID:19726882)
- Complete right bundle branch block (HP:0011712): A conduction block of the right branch of the bundle of His. This manifests as a prolongation of the QRS complex (greater than 0.12 s) with delayed activation of the right ventricle and terminal delay on the EKG. Evidence: IEA. Frequency: 19/71. (OMIM:604559)
- Arrhythmia (HP:0011675): Any cardiac rhythm other than the normal sinus rhythm. Such a rhythm may be either of sinus or ectopic origin and either regular or irregular. An arrhythmia may be due to a disturbance in impulse formation or conduction or both. Evidence: PCS. (PMID:19726882)
- Syncope (HP:0001279): A transient loss of consciousness (i.e., characterized by a rapid onset, a short duration, and a spontaneous and complete recovery) due to cerebral hypoperfusion. Evidence: TAS. (OMIM:604559)
- Atrioventricular block (HP:0001678): Delayed or lack of conduction of atrial depolarizations through the atrioventricular node to the ventricles. Evidence: PCS. (PMID:19726882)
- Autosomal dominant inheritance (HP:0000006): A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele. Evidence: PCS. (PMID:19726882)
These phenotypes are associated with the disease progressive familial heart block type IB (OMIM:604559).