Figure 1. A two-year-old boy came to medical attention because he lost consciousness four times over a period of five months. Three of the episodes occurred when the child became upset. These episodes had previously been diagnosed as “breath-holding spells.” He was also found to have severe sensorineural hearing loss. The child was taking no medication. There was no family history of sudden cardiac death. Panel A is a 12-lead electrocardiogram, showing marked prolongation of the QT interval (QT corrected for heart rate, 0.75 sec) with T-wave alternans. Panel B compares the flattened and diminished auditory evoked responses of this . . .