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Background

Mutations in the KCNJ2 gene, which codes cardiac and skeletal inward rectifying K⁺ channels (Kir2.1), produce Andersen’s syndrome, which is characterized by periodic paralysis, cardiac arrhythmia, and dysmorphic features.

Methods and Results

In 3 Japanese family members with periodic paralysis, ventricular arrhythmias, and marked QT prolongation, polymerase chain reaction/single-strand conformation polymorphism/DNA sequencing identified a novel, heterozygous, missense mutation in KCNJ2, Thr192Ala (T192A), which was located in the putative cytoplasmic chain after the second transmembrane region M2.

Using the Xenopus oocyte expression system, we found that the T192A mutant was nonfunctional in the homomeric condition. Coinjection with the wild-type gene reduced the current amplitude, showing a weak dominant-negative effect.

Conclusions

T192, which is located in the phosphatidylinositol-4,5-bisphosphate binding site and also the region necessary for Kir2.1 multimerization, is a highly conserved amino acid residue among inward-rectifier channels. We suggest that the T192A mutation resulted in the observed electrical phenotype.

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Key Words: arrhythmia • paralysis • ion channels • genes

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Circulation. 2002;105:2592

Tomohiko Ai, MD, PhD; Yuichiro Fujiwara, MD; Keiko Tsuji, BSc; Hideo Otani, MD; Shozo Nakano, MD, PhD; Yoshihiro Kubo, MD, PhD; Minoru Horie, MD, PhD

^{From the Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan (T.A., K.T., H.O., M.H.); the Department of Physiology, Tokyo Medical and Dental University, Tokyo, Japan (Y.F., Y.K.); and Ishimaru Pediatric Clinic, Matsuyama, Japan (S.N.).}

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Correspondence to Minoru Horie, MD, PhD, Division of Cardiac Electrophysiology, Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin, Kawahara Sakyo, Kyoto, Japan 606-8507. E-mail horie@kuhp.kyoto-u.ac.jp

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http://circ.ahajournals.org/cgi/content/abstract/105/22/2592