title: Non dominant-negative KCNJ2 gene mutations leading to Andersen-Tawil syndrome with an isolated cardiac phenotype.
abstract: Andersen-Tawil syndrome (ATS) is characterized by dysmorphic features, periodic paralyses and abnormal ventricular repolarization. After genotyping a large set of patients with congenital long-QT syndrome, we identified two novel, heterozygous KCNJ2 mutations (p.N318S, p.W322C) located in the C-terminus of the Kir2.1 subunit. These mutations have a different localization than classical ATS mutations which are mostly located at a potential interaction face with the slide helix or at the interface between the C-termini. Mutation carriers were without the key features of ATS, causing an isolated cardiac phenotype. While the N318S mutants regularly reached the plasma membrane, W322C mutants primarily resided in late endosomes. Co-expression of N318S or W322C with wild-type Kir2.1 reduced current amplitudes only by 20-25 %. This mild loss-of-function for the heteromeric channels resulted from defective channel trafficking (W322C) or gating (N318S). Strikingly, and in contrast to the majority of ATS mutations, neither mutant caused a dominant-negative suppression of wild-type Kir2.1, Kir2.2 and Kir2.3 currents. Thus, a mild reduction of native Kir2.x currents by non dominant-negative mutants may cause ATS with an isolated cardiac phenotype.
authors: Institut für Physiologie und Pathophysiologie, Vegetative Physiologie, Philipps-University Marburg, Deutschhausstraße 1-2, 35037 Marburg, Germany.
authors: Maren M
authors: MM
authors: Limberg
authors: Sven
authors: S
authors: Zumhagen
authors: Michael F
authors: MF
authors: Netter
authors: Alison J
authors: AJ
authors: Coffey
authors: Andrew
authors: A
authors: Grace
authors: Jane
authors: J
authors: Rogers
authors: Doris
authors: D
authors: Böckelmann
authors: Susanne
authors: S
authors: Rinné
authors: Birgit
authors: B
authors: Stallmeyer
authors: Niels
authors: N
authors: Decher
authors: Eric
authors: E
authors: Schulze-Bahr
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D050030:Andersen Syndrome / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D019556:COS Cells; D002648:Child; D002522:Chlorocebus aethiops; D004252:DNA Mutational Analysis; D004562:Electrocardiography; D005260:Female; D020022:Genetic Predisposition to Disease; D006339:Heart Rate / Q000235:genetics; D006579:Heterozygote; D006801:Humans; D008163:Luminescent Measurements; D008297:Male; D008958:Models, Molecular; D009154:Mutation; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010375:Pedigree; D010641:Phenotype; D024661:Potassium Channels, Inwardly Rectifying / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011487:Protein Conformation; D021381:Protein Transport; D013329:Structure-Activity Relationship; D013997:Time Factors; D014162:Transfection; D014982:Xenopus laevis
chemical_list: C489457:KCNJ2 protein, human; C099489:KCNJ4 protein, human; C489463:Kir2.2 channel; D024661:Potassium Channels, Inwardly Rectifying