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Gain-of-function mutation in TASK-4 channels and severe cardiac conduction disorder.

Friedrich C, Rinné S, Zumhagen S, Kiper AK, Silbernagel N, Netter MF, Stallmeyer B, Schulze-Bahr E, Decher N - EMBO Mol Med (2014)

Bottom Line: The heterozygous change (c.262G>A) resulted in the p.Gly88Arg mutation in the first extracellular pore loop.We demonstrate that KCNK17 is strongly expressed in human Purkinje cells and that overexpression of G88R leads to a hyperpolarization and strong slowing of the upstroke velocity of spontaneously beating HL-1 cells.Moreover, WES supports a second hit-hypothesis in severe arrhythmia cases and identified KCNK17 as a novel arrhythmia gene.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany.

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Heterozygous, digenic mutation state (KCNK17 and SCN5A) in patient 10192-1Electropherogram after direct sequencing of SCN5A: in the essential donor splice site located in intron 22, a heterozygous nucleic acid substitution was identified (c.3963+1G>A).Schematic topology of the Nav1.5 α-subunit. The affected splice site (black arrow) is located in the intracellular linker between the transmembrane segments S4 and S5 of domain 3 (DIII).Alignment of the boundary of exon 22/exon 23, position of the mutation is indicated by a black arrow. A skipping of exon 22 is predicted.Prioritization scheme for filtering variants obtained by whole-exome sequencing (WES). Minimum read depth was 20×. First, filtering of variants for relevant heart genes was done. Next, all variants with non-serious consequences (synonymous and mostly intronic changes) were excluded. Only unknown or rare alterations (MAF < 0.01%) were further evaluated with pathogenicity prediction programs (nsSNV: PolyPhen-2, SIFT, MutPred, SNPs&Go, SNAP; in-frame indels: SIFT/Provean; frameshift, splice site variants: Alamut). If all programs concordantly predict a damaging effect, the related gene was classified as a candidate gene. Discrepant prediction results lead to a classification as a variant of uncertain significance (VUS).Electropherogram after direct sequencing of KCNK17. A heterozygous nucleic acid substitution (c.262G>A) was detected in exon 2 of the KCNK17 gene.Schematic topology of the TASK-4 α-subunit with the point mutation p.Gly88Arg located in the extracellular linker between the first two transmembrane domains.Alignment illustrating the high degree of conservation of G88 between orthologs of TASK-4.
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fig02: Heterozygous, digenic mutation state (KCNK17 and SCN5A) in patient 10192-1Electropherogram after direct sequencing of SCN5A: in the essential donor splice site located in intron 22, a heterozygous nucleic acid substitution was identified (c.3963+1G>A).Schematic topology of the Nav1.5 α-subunit. The affected splice site (black arrow) is located in the intracellular linker between the transmembrane segments S4 and S5 of domain 3 (DIII).Alignment of the boundary of exon 22/exon 23, position of the mutation is indicated by a black arrow. A skipping of exon 22 is predicted.Prioritization scheme for filtering variants obtained by whole-exome sequencing (WES). Minimum read depth was 20×. First, filtering of variants for relevant heart genes was done. Next, all variants with non-serious consequences (synonymous and mostly intronic changes) were excluded. Only unknown or rare alterations (MAF < 0.01%) were further evaluated with pathogenicity prediction programs (nsSNV: PolyPhen-2, SIFT, MutPred, SNPs&Go, SNAP; in-frame indels: SIFT/Provean; frameshift, splice site variants: Alamut). If all programs concordantly predict a damaging effect, the related gene was classified as a candidate gene. Discrepant prediction results lead to a classification as a variant of uncertain significance (VUS).Electropherogram after direct sequencing of KCNK17. A heterozygous nucleic acid substitution (c.262G>A) was detected in exon 2 of the KCNK17 gene.Schematic topology of the TASK-4 α-subunit with the point mutation p.Gly88Arg located in the extracellular linker between the first two transmembrane domains.Alignment illustrating the high degree of conservation of G88 between orthologs of TASK-4.

Mentions: After sequencing the key genes (e.g., TRPM4, LMNA) for PCCD, we first identified in the SCN5A gene an unpublished, single nucleotide exchange in the essential donor splice site of intron 22 (c.3963+1G>A) (Fig 2A). The boundary between exon 22 and exon 23 is located in the intracellular linker between transmembrane segments S4 and S5 in domain 3 (DIII) of the Nav1.5 α-subunit (Fig 2A–C). In consequence, skipping of exon 22 is very likely, since a mutation affecting the same splice site (c.3963+2T>C, reported as IVS22+2T>C) was shown to cause exonic skipping and a complete loss of channel function (Schott et al, 1999).


Gain-of-function mutation in TASK-4 channels and severe cardiac conduction disorder.

Friedrich C, Rinné S, Zumhagen S, Kiper AK, Silbernagel N, Netter MF, Stallmeyer B, Schulze-Bahr E, Decher N - EMBO Mol Med (2014)

Heterozygous, digenic mutation state (KCNK17 and SCN5A) in patient 10192-1Electropherogram after direct sequencing of SCN5A: in the essential donor splice site located in intron 22, a heterozygous nucleic acid substitution was identified (c.3963+1G>A).Schematic topology of the Nav1.5 α-subunit. The affected splice site (black arrow) is located in the intracellular linker between the transmembrane segments S4 and S5 of domain 3 (DIII).Alignment of the boundary of exon 22/exon 23, position of the mutation is indicated by a black arrow. A skipping of exon 22 is predicted.Prioritization scheme for filtering variants obtained by whole-exome sequencing (WES). Minimum read depth was 20×. First, filtering of variants for relevant heart genes was done. Next, all variants with non-serious consequences (synonymous and mostly intronic changes) were excluded. Only unknown or rare alterations (MAF < 0.01%) were further evaluated with pathogenicity prediction programs (nsSNV: PolyPhen-2, SIFT, MutPred, SNPs&Go, SNAP; in-frame indels: SIFT/Provean; frameshift, splice site variants: Alamut). If all programs concordantly predict a damaging effect, the related gene was classified as a candidate gene. Discrepant prediction results lead to a classification as a variant of uncertain significance (VUS).Electropherogram after direct sequencing of KCNK17. A heterozygous nucleic acid substitution (c.262G>A) was detected in exon 2 of the KCNK17 gene.Schematic topology of the TASK-4 α-subunit with the point mutation p.Gly88Arg located in the extracellular linker between the first two transmembrane domains.Alignment illustrating the high degree of conservation of G88 between orthologs of TASK-4.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4119356&req=5

fig02: Heterozygous, digenic mutation state (KCNK17 and SCN5A) in patient 10192-1Electropherogram after direct sequencing of SCN5A: in the essential donor splice site located in intron 22, a heterozygous nucleic acid substitution was identified (c.3963+1G>A).Schematic topology of the Nav1.5 α-subunit. The affected splice site (black arrow) is located in the intracellular linker between the transmembrane segments S4 and S5 of domain 3 (DIII).Alignment of the boundary of exon 22/exon 23, position of the mutation is indicated by a black arrow. A skipping of exon 22 is predicted.Prioritization scheme for filtering variants obtained by whole-exome sequencing (WES). Minimum read depth was 20×. First, filtering of variants for relevant heart genes was done. Next, all variants with non-serious consequences (synonymous and mostly intronic changes) were excluded. Only unknown or rare alterations (MAF < 0.01%) were further evaluated with pathogenicity prediction programs (nsSNV: PolyPhen-2, SIFT, MutPred, SNPs&Go, SNAP; in-frame indels: SIFT/Provean; frameshift, splice site variants: Alamut). If all programs concordantly predict a damaging effect, the related gene was classified as a candidate gene. Discrepant prediction results lead to a classification as a variant of uncertain significance (VUS).Electropherogram after direct sequencing of KCNK17. A heterozygous nucleic acid substitution (c.262G>A) was detected in exon 2 of the KCNK17 gene.Schematic topology of the TASK-4 α-subunit with the point mutation p.Gly88Arg located in the extracellular linker between the first two transmembrane domains.Alignment illustrating the high degree of conservation of G88 between orthologs of TASK-4.
Mentions: After sequencing the key genes (e.g., TRPM4, LMNA) for PCCD, we first identified in the SCN5A gene an unpublished, single nucleotide exchange in the essential donor splice site of intron 22 (c.3963+1G>A) (Fig 2A). The boundary between exon 22 and exon 23 is located in the intracellular linker between transmembrane segments S4 and S5 in domain 3 (DIII) of the Nav1.5 α-subunit (Fig 2A–C). In consequence, skipping of exon 22 is very likely, since a mutation affecting the same splice site (c.3963+2T>C, reported as IVS22+2T>C) was shown to cause exonic skipping and a complete loss of channel function (Schott et al, 1999).

Bottom Line: The heterozygous change (c.262G>A) resulted in the p.Gly88Arg mutation in the first extracellular pore loop.We demonstrate that KCNK17 is strongly expressed in human Purkinje cells and that overexpression of G88R leads to a hyperpolarization and strong slowing of the upstroke velocity of spontaneously beating HL-1 cells.Moreover, WES supports a second hit-hypothesis in severe arrhythmia cases and identified KCNK17 as a novel arrhythmia gene.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany.

Show MeSH
Related in: MedlinePlus