Table 2.

Clinical characteristics of KCNQ1 homozygotes/compound heterozygotes referred to Mayo Clinic for evaluation

Variable	All cases	“Recessive” LQT1	JLNS
Clinical demographics and family history
Patients, n (%)	15 (100)	11 (73)	4 (27)
Male/female, n	7/8	6/5	2/2
Age at diagnosis, years	7.0 ± 9.5	8.8 ± 11.0	2.0 ± 2.7
Family history of LQTS/sudden death, n (%)	11 (73)	10 (91)#	1 (25)
Bilateral sensorineural deafness, n (%)	4 (27)	0 (0)	4 (100)*
Symptomatology
Any cardiac event (%)	13 (87)	11 (100)	2 (50)
Syncope, n (%)	13 (87)	11 (100)	2 (50)
Documented TdP/VF, n (%)	5 (39)	4 (36)	2 (50)
Out of hospital cardiac arrest, n (%)	2 (15)	3 (27)	0 (0)
QTc (ms)	557 ± 60	560 ± 69	549 ± 29
Clinical management
β-blockers, n (%)	15 (100)	11 (100)	4 (100)
Implantable cardioverter-defibrillator, n (%)	8 (53)	6 (55)	2 (50)
Left cardiac sympathetic denervation, n (%)	11 (73)	7 (64)	4 (100)

Clinical characteristic and management values are expressed as number of patients (percentage of total) or as mean ± standard deviation. All ECG parameters represent mean ± standard deviation.

^#P ≤ 0.05 compared to JLNS cases.

^*P ≤ 0.05 compared to AR LQT1 cases.

Abbreviations: JLNS, Jervell and Lange-Nielsen syndrome; LQT1, type 1 long QT syndrome; TdP, torsades de pointes; VF, ventricular fibrillation.