Fig. 2

The molecular and clinical findings for family II and family III, and KCNQ1 mutations illustrated on KCNQ1 protein (a) Pedigree of the family II; Case 2 (III-5) who is carrying compound heterozygous mutations of c.477 + 1G > A and c.520C > T (p.Arg174Cys) in KCNQ1 gene and the carrier status of the other family members were shown above, (N = Normal, +: Mutant allele, −: Normal allele), DNA sequencing images of the mutations in the proband were presented below (b) The ECG of the proband (III-5) in family II showing the prolongation of QTc (530 ms) interval (c) Pedigree of the family III; Case 3 (IV-5) who is carrying the c.1097G > A (p.R366Q) mutation in KCNQ1 gene and the carrier status of the other family members were presented (N = Normal, SUD = Sudden unidentified death, NT = Not tested, +:Mutant allele, −:Normal allele) (d) The ECG of the proband (IV-5) in family III showing the prolongation of QTc (520 ms) (e) The illustration showing all of the KCNQ1 mutations seen in our three cases (S1, S2, S3, S5,S6: Helical, transmembranic domains; S4:Helical, Voltage-sensor, transmembranic domain; H5: Pore-forming, intramembranic domain)