- Ventricular fibrillation (HP:0001663): Uncontrolled contractions of muscles fibers in the left ventricle not producing contraction of the left ventricle. Ventricular fibrillation usually begins with a ventricular premature contraction and a short run of rapid ventricular tachycardia degenerating into uncoordinating ventricular fibrillations. Evidence: PCS. Frequency: 2/3. (PMID:10219239)
- Cardiac arrest (HP:0001695): An abrupt loss of heart function. Evidence: PCS. Frequency: 2/3. (PMID:10219239)
- Adult onset (HP:0003581): Onset of disease manifestations in adulthood, defined here as at the age of 16 years or later. Evidence: PCS. Frequency: 3/3. (PMID:10219239)
- 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: TAS. (OMIM:613693)
- Prolonged QTc interval (HP:0005184): A longer than normal interval (corrected for heart rate) between the Q and T waves in the heart's cycle. Prolonged QTc can cause premature action potentials during late phase depolarizations thereby leading to ventricular arrhythmias and ventricular fibrillations. Evidence: PCS. Frequency: 3/3. (PMID:10219239)
- 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:613693)
- Torsade de pointes (HP:0001664): A type of ventricular tachycardia characterized by polymorphioc QRS complexes that change in amplitue and cycle length, and thus have the appearance of oscillating around the baseline in the EKG. Evidence: PCS. Frequency: 1/3. (PMID:10219239)
- Sudden cardiac death (HP:0001645): The heart suddenly and unexpectedly stops beating resulting in death within a short time period (generally within 1 h of symptom onset). Evidence: TAS. (OMIM:613693)
- 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:10219239)
These phenotypes are associated with the disease long QT syndrome 6 (OMIM:613693).