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Andersen Syndrome

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Woodrow D Benson – One of the best experts on this subject based on the ideXlab platform.

  • trafficking competent and trafficking defective kcnj2 mutations in Andersen Syndrome
    Human Mutation, 2006
    Co-Authors: Leomar Y. Ballester, Woodrow D Benson, Carlos G. Vanoye, Brenda Wong, Ian H. Law, Katherine D. Mathews, Alfred L George

    Abstract:

    Mutations in KCNJ2, the gene encoding the human inward rectifier potassium channel Kir2.1, have been identified in Andersen Syndrome (or Andersen-Tawil Syndrome), an inherited disorder characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features. We identified and characterized two novel KCNJ2 mutations (c.220A>G/p.T74A and c.443G>C/p.G144A) associated with Andersen Syndrome. Heterologous expression of a recombinant wild type human KCNJ2 cDNA (WT-KCNJ2) in HEK-293 cells results in robust inward rectifying currents, but we did not observe measurable currents from cells expressing either mutant. Cells co-transfected with WT-KCNJ2 and either mutant exhibited substantially lower whole-cell current amplitude consistent with a dominant-negative suppression of WT-KCNJ2 by the mutant channels. Both p.T74A and p.G144A exhibit robust plasma membrane expression, but a third previously reported allele (p.C101R) exhibited impaired trafficking. Our results demonstrate functional consequences of two novel trafficking-competent KCNJ2 mutations associated with Andersen Syndrome and expand our knowledge of allelic diversity in this disease. Published 2006 Wiley-Liss, Inc.

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  • kcnj2 mutation results in Andersen Syndrome with sex specific cardiac and skeletal muscle phenotypes
    American Journal of Human Genetics, 2002
    Co-Authors: Gregor Andelfinger, Andrew R Tapper, Richard C Welch, Carlos G. Vanoye, Alfred L George, Woodrow D Benson

    Abstract:

    Evaluation of candidate loci culminated in the identification of a heterozygous missense mutation (R67W) in KCNJ2, the gene encoding the inward-rectifying potassium current, Kir2.1, in 41 members of a kindred in which ventricular arrhythmias (13 of 16 female members [81%]) and periodic paralysis (10 of 25 male members [40%]) segregated as autosomal dominant traits with sex-specific variable expressivity. Some mutation carriers exhibited dysmorphic features, including hypertelorism, small mandible, syndactyly, clinodactyly, cleft palate, and scoliosis, which, together with cardiodysrhythmic periodic paralysis, have been termed “Andersen Syndrome.” However, no individual exhibited all manifestations of Andersen Syndrome, and this diagnosis was not considered in the proband until other family members were examined. Other features seen in this kindred included unilateral dysplastic kidney and cardiovascular malformation (i.e., bicuspid aortic valve, bicuspid aortic valve with coarctation of the aorta, or valvular pulmonary stenosis), which have not been previously associated. Nonspecific electrocardiographic abnormalities were identified in some individuals, but none had a prolonged QT interval. Biophysical characterization of R67W demonstrated loss of function and a dominant-negative effect on Kir2.1 current. These findings support the suggestion that, in addition to its recognized role in function of cardiac and skeletal muscle, KCNJ2 plays an important role in developmental signaling.

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  • kcnj2 mutation results in Andersen Syndrome with sex specific cardiac and skeletal muscle phenotypes
    American Journal of Human Genetics, 2002
    Co-Authors: Gregor Andelfinger, Andrew R Tapper, Richard C Welch, Carlos G. Vanoye, Alfred L George, Woodrow D Benson

    Abstract:

    Evaluation of candidate loci culminated in the identification of a heterozygous missense mutation (R67W) in KCNJ2, the gene encoding the inward-rectifying potassium current, Kir2.1, in 41 members of a kindred in which ventricular arrhythmias (13 of 16 female members [81%]) and periodic paralysis (10 of 25 male members [40%]) segregated as autosomal dominant traits with sex-specific variable expressivity. Some mutation carriers exhibited dysmorphic features, including hypertelorism, small mandible, syndactyly, clinodactyly, cleft palate, and scoliosis, which, together with cardiodysrhythmic periodic paralysis, have been termed “Andersen Syndrome.” However, no individual exhibited all manifestations of Andersen Syndrome, and this diagnosis was not considered in the proband until other family members were examined. Other features seen in this kindred included unilateral dysplastic kidney and cardiovascular malformation (i.e., bicuspid aortic valve, bicuspid aortic valve with coarctation of the aorta, or valvular pulmonary stenosis), which have not been previously associated. Nonspecific electrocardiographic abnormalities were identified in some individuals, but none had a prolonged QT interval. Biophysical characterization of R67W demonstrated loss of function and a dominant-negative effect on Kir2.1 current. These findings support the suggestion that, in addition to its recognized role in function of cardiac and skeletal muscle, KCNJ2 plays an important role in developmental signaling.

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Alfred L George – One of the best experts on this subject based on the ideXlab platform.

  • Exaggerated Mg2+ inhibition of Kir2.1 as a consequence of reduced PIP2 sensitivity in Andersen Syndrome.
    Channels, 2007
    Co-Authors: Leomar Y. Ballester, Carlos G. Vanoye, Alfred L George

    Abstract:

    Andersen Syndrome is an autosomal dominant disorder characterized by cardiac arrhythmias, periodic paralysis and dysmorphic features. Many Andersen Syndrome cases have been associated with loss-of-function mutations in the inward rectifier K+ channel Kir2.1 encoded by KCNJ2. Using engineered concatenated tetrameric channels we determined the mechanism for dominant loss-of-function associated with a trafficking-competent missense mutation, Kir2.1-T74A. This mutation alters a conserved threonine residue in an N-terminal domain analogous to the slide helix identified in the structure of a bacterial inward rectifier. Incorporation of a single mutant subunit in channel tetramers was sufficient to cause a selective impairment of whole-cell outward current, but no difference in the level of inward current compared with wild-type (WT) tetramers. The presence of two mutant subunits resulted in greatly reduced outward and impaired inward currents. Experiments using excised inside-out membrane patches revealed that …

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  • trafficking competent and trafficking defective kcnj2 mutations in Andersen Syndrome
    Human Mutation, 2006
    Co-Authors: Leomar Y. Ballester, Woodrow D Benson, Carlos G. Vanoye, Brenda Wong, Ian H. Law, Katherine D. Mathews, Alfred L George

    Abstract:

    Mutations in KCNJ2, the gene encoding the human inward rectifier potassium channel Kir2.1, have been identified in Andersen Syndrome (or Andersen-Tawil Syndrome), an inherited disorder characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features. We identified and characterized two novel KCNJ2 mutations (c.220A>G/p.T74A and c.443G>C/p.G144A) associated with Andersen Syndrome. Heterologous expression of a recombinant wild type human KCNJ2 cDNA (WT-KCNJ2) in HEK-293 cells results in robust inward rectifying currents, but we did not observe measurable currents from cells expressing either mutant. Cells co-transfected with WT-KCNJ2 and either mutant exhibited substantially lower whole-cell current amplitude consistent with a dominant-negative suppression of WT-KCNJ2 by the mutant channels. Both p.T74A and p.G144A exhibit robust plasma membrane expression, but a third previously reported allele (p.C101R) exhibited impaired trafficking. Our results demonstrate functional consequences of two novel trafficking-competent KCNJ2 mutations associated with Andersen Syndrome and expand our knowledge of allelic diversity in this disease. Published 2006 Wiley-Liss, Inc.

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  • Trafficking‐competent and trafficking‐defective KCNJ2 mutations in Andersen Syndrome
    Human Mutation, 2006
    Co-Authors: Leomar Y. Ballester, Carlos G. Vanoye, D. Woodrow Benson, Brenda Wong, Ian H. Law, Katherine D. Mathews, Alfred L George

    Abstract:

    Mutations in KCNJ2, the gene encoding the human inward rectifier potassium channel Kir2.1, have been identified in Andersen Syndrome (or Andersen-Tawil Syndrome), an inherited disorder characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features. We identified and characterized two novel KCNJ2 mutations (c.220A>G/p.T74A and c.443G>C/p.G144A) associated with Andersen Syndrome. Heterologous expression of a recombinant wild type human KCNJ2 cDNA (WT-KCNJ2) in HEK-293 cells results in robust inward rectifying currents, but we did not observe measurable currents from cells expressing either mutant. Cells co-transfected with WT-KCNJ2 and either mutant exhibited substantially lower whole-cell current amplitude consistent with a dominant-negative suppression of WT-KCNJ2 by the mutant channels. Both p.T74A and p.G144A exhibit robust plasma membrane expression, but a third previously reported allele (p.C101R) exhibited impaired trafficking. Our results demonstrate functional consequences of two novel trafficking-competent KCNJ2 mutations associated with Andersen Syndrome and expand our knowledge of allelic diversity in this disease. Published 2006 Wiley-Liss, Inc.

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Carlos G. Vanoye – One of the best experts on this subject based on the ideXlab platform.

  • Exaggerated Mg2+ inhibition of Kir2.1 as a consequence of reduced PIP2 sensitivity in Andersen Syndrome.
    Channels, 2007
    Co-Authors: Leomar Y. Ballester, Carlos G. Vanoye, Alfred L George

    Abstract:

    Andersen Syndrome is an autosomal dominant disorder characterized by cardiac arrhythmias, periodic paralysis and dysmorphic features. Many Andersen Syndrome cases have been associated with loss-of-function mutations in the inward rectifier K+ channel Kir2.1 encoded by KCNJ2. Using engineered concatenated tetrameric channels we determined the mechanism for dominant loss-of-function associated with a trafficking-competent missense mutation, Kir2.1-T74A. This mutation alters a conserved threonine residue in an N-terminal domain analogous to the slide helix identified in the structure of a bacterial inward rectifier. Incorporation of a single mutant subunit in channel tetramers was sufficient to cause a selective impairment of whole-cell outward current, but no difference in the level of inward current compared with wild-type (WT) tetramers. The presence of two mutant subunits resulted in greatly reduced outward and impaired inward currents. Experiments using excised inside-out membrane patches revealed that …

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  • trafficking competent and trafficking defective kcnj2 mutations in Andersen Syndrome
    Human Mutation, 2006
    Co-Authors: Leomar Y. Ballester, Woodrow D Benson, Carlos G. Vanoye, Brenda Wong, Ian H. Law, Katherine D. Mathews, Alfred L George

    Abstract:

    Mutations in KCNJ2, the gene encoding the human inward rectifier potassium channel Kir2.1, have been identified in Andersen Syndrome (or Andersen-Tawil Syndrome), an inherited disorder characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features. We identified and characterized two novel KCNJ2 mutations (c.220A>G/p.T74A and c.443G>C/p.G144A) associated with Andersen Syndrome. Heterologous expression of a recombinant wild type human KCNJ2 cDNA (WT-KCNJ2) in HEK-293 cells results in robust inward rectifying currents, but we did not observe measurable currents from cells expressing either mutant. Cells co-transfected with WT-KCNJ2 and either mutant exhibited substantially lower whole-cell current amplitude consistent with a dominant-negative suppression of WT-KCNJ2 by the mutant channels. Both p.T74A and p.G144A exhibit robust plasma membrane expression, but a third previously reported allele (p.C101R) exhibited impaired trafficking. Our results demonstrate functional consequences of two novel trafficking-competent KCNJ2 mutations associated with Andersen Syndrome and expand our knowledge of allelic diversity in this disease. Published 2006 Wiley-Liss, Inc.

    Free Register to Access Article

  • Trafficking‐competent and trafficking‐defective KCNJ2 mutations in Andersen Syndrome
    Human Mutation, 2006
    Co-Authors: Leomar Y. Ballester, Carlos G. Vanoye, D. Woodrow Benson, Brenda Wong, Ian H. Law, Katherine D. Mathews, Alfred L George

    Abstract:

    Mutations in KCNJ2, the gene encoding the human inward rectifier potassium channel Kir2.1, have been identified in Andersen Syndrome (or Andersen-Tawil Syndrome), an inherited disorder characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features. We identified and characterized two novel KCNJ2 mutations (c.220A>G/p.T74A and c.443G>C/p.G144A) associated with Andersen Syndrome. Heterologous expression of a recombinant wild type human KCNJ2 cDNA (WT-KCNJ2) in HEK-293 cells results in robust inward rectifying currents, but we did not observe measurable currents from cells expressing either mutant. Cells co-transfected with WT-KCNJ2 and either mutant exhibited substantially lower whole-cell current amplitude consistent with a dominant-negative suppression of WT-KCNJ2 by the mutant channels. Both p.T74A and p.G144A exhibit robust plasma membrane expression, but a third previously reported allele (p.C101R) exhibited impaired trafficking. Our results demonstrate functional consequences of two novel trafficking-competent KCNJ2 mutations associated with Andersen Syndrome and expand our knowledge of allelic diversity in this disease. Published 2006 Wiley-Liss, Inc.

    Free Register to Access Article