- 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: TAS. Frequency: Obligate (HP:0040280). (ORPHA:101016)
- 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. Frequency: Frequent (HP:0040282). (ORPHA:101016)
- Sinus bradycardia (HP:0001688): Bradycardia related to a mean resting sinus rate of less than 50 beats per minute. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:101016)
- Abnormal T-wave (HP:0005135): An abnormality of the T wave on the electrocardiogram, which mainly represents the repolarization of the ventricles. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:101016)
- Seizure (HP:0001250): A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:101016)
- 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. Frequency: Occasional (HP:0040283). (ORPHA:101016)
- 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: TAS. Frequency: Occasional (HP:0040283). (ORPHA:101016)
- Ventricular arrhythmia (HP:0004308). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:101016)
- Abnormal autonomic nervous system physiology (HP:0012332): A functional abnormality of the autonomic nervous system. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:101016)
- Abnormal cardiac exercise stress test (HP:0500018): Abnormal results of exercise on heart function. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:101016)
- Abnormality of prenatal development or birth (HP:0001197): An abnormality of the fetus or the birth of the fetus, excluding structural abnormalities. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:101016)
- Hypokalemia (HP:0002900): The concentration of potassium(1+) in the blood circulation is below the lower limit of normal. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:101016)
These phenotypes are associated with the disease Romano-Ward syndrome (ORPHA:101016).
The following phenotypes are NOT associated with this disease:
- Hearing impairment (HP:0000365): A decreased magnitude of the sensory perception of sound. Evidence: TAS. (ORPHA:101016)