Cluster 350: personal history family syndrome qt long cancer crc melanoma participants 
Cluster 680: qt syndrome long history family interval risk subject prolonged tdp 
Cluster 865: congenital qt long syndrome history diagnosed family suspected sudden patients 
Cluster 986: qt prolongation interval risk long qtc syndrome arrhythmic heart factors 
Cluster 2184: qtc family history long syndrome personal ventricular prolongation bigeminy msec