ORPHA: 51083; DO: 0050793;
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
Gene/Locus |
Gene/Locus MIM number |
|---|---|---|---|---|---|---|
| 17q24.3 | Short QT syndrome 3 | 609622 | Autosomal dominant | 3 | KCNJ2 | 600681 |
A number sign (#) is used with this entry because of evidence that short QT syndrome-3 (SQT3) is caused by heterozygous mutation in the KCNJ2 gene (600681) on chromosome 17q24.
Short QT syndrome is a cardiac channelopathy associated with a predisposition to atrial fibrillation and sudden cardiac death. Patients have a structurally normal heart, but electrocardiography (ECG) exhibits abbreviated QTc (Bazett's corrected QT) intervals of less than 360 ms (summary by Moreno et al., 2015).
For a discussion of genetic heterogeneity of short QT syndrome, see SQT1 (609620).
Priori et al. (2005) reported an asymptomatic 5-year-old girl who was found to have an abnormal ECG on routine clinical evaluation, with a markedly short repolarization time and conspicuously narrow and peaked T waves (QTc interval, 315 ms). Investigation of the family revealed that her 35-year-old father had a short QT interval (320 ms) and a history of presyncopal episodes and palpitations since age 15. ECGs of the proband and her father were characterized by asymmetric T waves with a fairly normal ascending phase and a remarkably rapid terminal phase, a pattern that was consistently present and could be seen in the first ECG of the father at age 15. The mother and the paternal grandparents had unremarkable ECGs and reported no family histories of sudden death.
Hattori et al. (2012) reported an 8-year-old Japanese girl with a markedly short QT interval and mutation in the KCNJ2 gene. During a routine checkup she was found to have an irregular heart beat, and electrocardiogram (ECG) showed atrial fibrillation (AF). Echocardiogram was normal. During right heart catheterization, insertion of the catheter into the right atrium induced supraventricular tachycardia, and ventricular fibrillation (VF) occurred at the position of the right outflow tract. She was diagnosed with SQTS based on her markedly shortened QT interval (QTc, 194 ms), paroxysmal AF, and VF inducibility. Other features in the proband included severe mental retardation, abnormal proliferation of esophageal blood vessels, epilepsy, and Kawasaki disease (see 611775). Family history revealed that an older sister had died at 7 hours after birth. ECGs of her father and 2 sibs showed normal QT intervals. The authors stated that the proband's QT interval was the shortest among previously published SQTS reports.
Deo et al. (2013) reported an 11-year-old boy with paroxysmal AF, mild left ventricular dysfunction, short QT interval, and mutation in the KCNJ2 gene. The proband had his first episode of AF at age 8 years. An abnormally short QT interval (200 ms) was seen on ECG, which showed a QRS merged with the T wave, and absence of a distinct ST segment in all leads. Peaked T waves were present, particularly in the left precordial leads. Holter recording showed episodes of paroxysmal AF, with an average ventricular response of 98 beats per minute (range, 54 to 172 bpm), and confirmed the presence of a short QT interval that did not adapt to heart rate changes. Cardiac MRI showed normal volumes of the 4 chambers, but mild to moderate hypokinesis in all segments of both ventricles with reduced ejection fractions. At follow-up after cardioversion and maintenance of sinus rhythm with medication, the ejection fractions had recovered and left ventricular hypokinesis had resolved, suggesting that both were likely related to a cardiomyopathy caused by the rapid AF rate. His parents had unremarkable ECGs and there was no family history of sudden death.
In a 5-year-old girl and her father who had short QT intervals and asymmetric T waves on ECG and who were negative for mutations in the 2 genes previously associated with short QT syndrome, KCNH2 and KCNQ1, Priori et al. (2005) identified a heterozygous missense mutation in the KCNJ2 gene (D172N; 600681.0010). The mutation was not present in the unaffected mother or in the paternal grandparents, indicating that it may have occurred de novo in the father.
Schimpf et al. (2005) reviewed the clinical, electrophysiologic, and molecular features of 15 reported cases and 2 unpublished cases of short QT syndrome types 1, 2 (609621), and 3.
In an 8-year-old Japanese girl with a markedly short QT interval, Hattori et al. (2012) screened known cardiac ion channel genes and identified heterozygosity for a missense mutation in the KCNJ2 gene (M301K; 600681.0015). Family DNA was unavailable for study, but the variant was not found in 400 Japanese control alleles. Noting that KCNJ2 is expressed in a variety of tissues, the authors suggested that the proband's extracardiac features, including severe intellectual disability and seizures, might be attributed to the KCNJ2 variant, but stated that they could not exclude the possibility of other mutated genes.
In an 11-year-old boy with an abnormally short QT interval, Deo et al. (2013) analyzed an SQTS screening panel and identified a missense mutation in the KCNJ2 gene (E299V; 600681.0016). The mutation was not found in his parents or in 400 control individuals.
Deo, M., Ruan, Y., Pandit, S. V., Shah, K., Berenfeld, O., Blaufox, A., Cerrone, M., Noujaim, S. F., Denegri, M., Jalife, J., Priori, S. G. KCNJ2 mutation in short QT syndrome 3 results in atrial fibrillation and ventricular proarrhythmia. Proc. Nat. Acad. Sci. 110: 4291-4296, 2013. [PubMed: 23440193] [Full Text: https://doi.org/10.1073/pnas.1218154110]
Hattori, T., Makiyama, T., Akao, M., Ehara, E., Ohno, S., Iguchi, M., Nishio, Y., Sasaki, K., Itoh, H., Yokode, M., Kita, T., Horie, M., Kimura, T. A novel gain-of-function KCNJ2 mutation associated with short-QT syndrome impairs inward rectification of Kir2.1 currents. Cardiovasc. Res. 93: 666-673, 2012. [PubMed: 22155372] [Full Text: https://doi.org/10.1093/cvr/cvr329]
Moreno, C., Oliveras, A., de la Cruz, A., Bartolucci, C., Munoz, C., Salar, E., Gimeno, J. R., Severi, S., Comes, N., Felipe, A., Gonzalez, T., Lambiase, P., Valenzuela, C. A new KCNQ1 mutation at the S5 segment that impairs its association with KCNE1 is responsible for short QT syndrome. Cardiovasc. Res. 107: 613-623, 2015. [PubMed: 26168993] [Full Text: https://doi.org/10.1093/cvr/cvv196]
Priori, S. G., Pandit, S. V., Rivolta, I., Berenfeld, O., Ronchetti, E., Dhamoon, A., Napolitano, C., Anumonwo, J., Raffaele di Barletta, M., Gudapakkam, S., Bosi, G., Stramba-Badiale, M., Jalife, J. A novel form of short QT syndrome (SQT3) is caused by a mutation in the KCNJ2 gene. Circ. Res. 96: 800-807, 2005. [PubMed: 15761194] [Full Text: https://doi.org/10.1161/01.RES.0000162101.76263.8c]
Schimpf, R., Wolpert, C., Gaita, F., Giustetto, C., Borggrefe, M. Short QT syndrome. Cardiovasc. Res. 67: 357-366, 2005. [PubMed: 15890322] [Full Text: https://doi.org/10.1016/j.cardiores.2005.03.026]