Missense mutations in the transmembrane helix of Kv7.1 (KCNQ1) are found in patients with long-QT syndrome, and some mutations, such as Ala341 (Gly104 in KcsA) to Val and Leu342 (Leu105 in KcsA) to Phe, have increased side-chain volumes in the region around the hot spot residues46–48. Here, KCNQ1 is linked to Prolonged QT interval.