Short QT syndrome classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Five variants of short QT syndrome have been characterized based upon the underlying genetic mutation, the electrocardiographic phenotype, and the clinical manifestations of the variant.
Short QT syndrome type 1 (SQT1)
This variant is due to a gain-of-function mutation of the rapid component of the delayed rectifier potassium current HERG (KCNH2) channel(IKr)[1]. The variant is a result of missense mutations which increase IKr. It is associated with sudden death and sudden infant death syndrome.
Short QT syndrome type 2 (SQT2)
Caused by a mutation in the KCNQ1 gene[2]. In the first patient, a g919c substitution in the KCNQ1 gene encoding for the K+ channel KvLQT1 was identified. The mutation led to a gain of function in in the KvLQT1 (I(Ks)) channel. This variant is associated with ventricular fibrillation.
Short QT syndrome type 3 (SQT3)
This variant results from a G514A substitution in the KCNJ2 gene ( a change from aspartic acid to asparagine at position 172 (D172N))[3]. This causes a defect in the gene coding for the inwardly rectifying Kir2.1 (I(K1)) channel. The ECG shows asymmetrical T waves. These patients have an increased risk for re-entry arrhythmias.
Short QT syndrome type 4 (SQT4)
A loss of function mutation in the CACNA1C gene alters the encoding for the α1- and β2b-subunits of the L-type calcium channel. The phenotype is similar to Brugada syndrome combined with a short QT interval. There is an increased risk of sudden cardiac death.
Short QT syndrome type 5 (SQT5)
A loss of function mutation in the CACNB2B gene alters the encoding for the α1- and β2b-subunits of the L-type calcium channel. The phenotype is similar to Brugada syndrome combined with a short QT interval. There is an increased risk of sudden cardiac death.
References
- ↑ Brugada R, Hong K, Dumaine R, Cordeiro J, Gaita F, Borggrefe M, Menendez TM, Brugada J, Pollevick GD, Wolpert C, Burashnikov E, Matsuo K, Wu YS, Guerchicoff A, Bianchi F, Giustetto C, Schimpf R, Brugada P, Antzelevitch C (2004). "Sudden death associated with short-QT syndrome linked to mutations in HERG". Circulation. 109 (1): 30–5. doi:10.1161/01.CIR.0000109482.92774.3A. PMID 14676148. Retrieved 2012-09-02. Unknown parameter
|month=ignored (help) - ↑ Bellocq C, van Ginneken AC, Bezzina CR, Alders M, Escande D, Mannens MM, Baró I, Wilde AA (2004). "Mutation in the KCNQ1 gene leading to the short QT-interval syndrome". Circulation. 109 (20): 2394–7. doi:10.1161/01.CIR.0000130409.72142.FE. PMID 15159330. Retrieved 2012-09-02. Unknown parameter
|month=ignored (help) - ↑ Priori SG, Pandit SV, Rivolta I, Berenfeld O, Ronchetti E, Dhamoon A, Napolitano C, Anumonwo J, di Barletta MR, Gudapakkam S, Bosi G, Stramba-Badiale M, Jalife J (2005). "A novel form of short QT syndrome (SQT3) is caused by a mutation in the KCNJ2 gene". Circulation Research. 96 (7): 800–7. doi:10.1161/01.RES.0000162101.76263.8c. PMID 15761194. Retrieved 2012-09-02. Unknown parameter
|month=ignored (help)