KCNH2 and familial long QT syndrome: Standard variant analysis showed that the patient is heterozygous for the pathogenic rs199473022 T allele, a rare variant causing a Gly1036Asp substitution in the ion channel encoded by the gene KCNH2. This was first identified in one of 541 Long QT Syndrome (LQTS) patients, but not in any of 750 controls [48].