rs1800171
Variant summary
Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM2_SupportingPS3PS4PP3PP4
This summary comes from the ClinGen Evidence Repository: NM_000218.3(KCNQ1):c.1032G>A is a synonymous variant (p.Ala344=) predicted to affect KCNQ1 mRNA splicing. The computational splicing predictor SpliceAI gives scores of 0.49 for donor gain and 0.38 for donor loss, which are higher than the ClinGen Potassium Channel Arrhythmia VCEP PP3 threshold of greater than or equal to 0.2 and predict that the variant disrupts KCNQ1 splicing (PP3). The variant is observed at an extremely low frequency in the population with a maximum allele frequency (gnomAD 4.1.0) of 0.000001701, with 2 in 1,175,668 individuals of European (non-Finnish) ancestry (PM2_Supporting). Functional studies have been performed on this variant and meet criteria with demonstrated deleterious effects on electrophysiology and RNA metabolism (PS3, PMID:29857160, 10477533, 17292394). There are 23 reported probands in the literature with a clinical diagnosis of Long QT syndrome (PS4; PMID:26118460, PMID:21810471, PMID:9654228, PMID:29497013, PMID:17292394). An additional case reports provides specific details that are highly specific for a diagnosis of Long QT syndrome in an individual with the variant who had a significantly prolonged QTc at rest and exercise-triggered events (PP4, PMID:21810471). In summary, this variant meets the criteria to be classified as pathogenic for long QT syndrome 1 based on the ACMG/AMP criteria applied, as specified by the ClinGen Potassium Channel Arrhythmia VCEP: PS3, PS4, PM2_Supporting, PP3, and PP4. (VCEP specifications version 1.0.0; date of approval 03/04/2025). LINK:https://erepo.genome.network/evrepo/ui/classification/CA005005/MONDO:0100316/112
Frequency
Consequence
NM_000218.3 splice_region, synonymous
Scores
Clinical Significance
Conservation
Publications
- long QT syndromeInheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
- long QT syndrome 1Inheritance: AD, AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
- Jervell and Lange-Nielsen syndromeInheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
- Jervell and Lange-Nielsen syndrome 1Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: PanelApp Australia, Labcorp Genetics (formerly Invitae), G2P
- atrial fibrillation, familial, 3Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
- short QT syndromeInheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: ClinGen, Orphanet
- short QT syndrome type 2Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
- familial atrial fibrillationInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- Jervell and Lange-Nielsen syndromeInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- hypertrophic cardiomyopathyInheritance: AD Classification: NO_KNOWN Submitted by: ClinGen
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ACMG classification
Our verdict: Pathogenic. The variant received 11 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.00000657 AC: 1AN: 152222Hom.: 0 Cov.: 33 show subpopulations
GnomAD2 exomes AF: 0.00000398 AC: 1AN: 251186 AF XY: 0.00000736 show subpopulations
GnomAD4 exome AF: 6.86e-7 AC: 1AN: 1456938Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1AN XY: 725086 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.00000657 AC: 1AN: 152222Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0AN XY: 74362 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
Long QT syndrome 1 Pathogenic:7
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The variant is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: <0.001%). Functional studies provide moderate evidence of the variant having a damaging effect on the gene or gene product (PMID:10477533, 21810471). The variant has been observed in multiple (>3) similarly affected unrelated individuals (PMID:10477533, 21810471, 27485560, 29255176, 31589614, 31737537). The variant has been reported to co-segregate with the disease in at least 5 similarly affected relatives/individuals in the same family or similarly affected unrelated families (PMID:10477533).Therefore, this variant is classified as pathogenic according to the recommendation of ACMG/AMP guideline. -
Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0103 - Dominant negative, loss of function and gain of function are known mechanisms of disease in this gene. Gain of function variants result exclusively in Short QT syndrome (MIM#609621), while dominant negative and loss of function variants can cause Long QT syndrome (LQTS, MIM#192500), atrial fibrillation (MIM#607554) and Jervell and Lange-Nielsen syndrome (JLNS, MIM#220400) (OMIM, PMIDs: 19632626, 28438721). (I) 0108 - This gene is known to be associated with both recessive and dominant disease. JLNS is characterized by congenital, bilateral deafness and variable degrees of QT prolongation, and is the only condition caused by biallelic mutations (PMID: 28438721). (I) 0112 - The condition associated with this gene has incomplete penetrance (GeneReviews, OMIM). (I) 0209 - Splice site variant proven to affect splicing of the transcript with uncertain effect on protein sequence. This variant has been shown to result in several splicing errors, including the skipping of exon 7, exon 8, or both exon 7 and 8. Quantitative analysis confirmed only 55% of wildtype transcript remained (PMID: 21810471). (SP) 0251 - This variant is heterozygous. (I) 0302 - Variant is present in gnomAD (v2, v3) <0.001 for a dominant condition (1 heterozygote, 0 homozygotes). (SP) 0602 - Variant is located in a hotspot region or cluster of pathogenic variants. Multiple pathogenic variants at the same residue have been reported as pathogenic, and it is described as the 2nd most mutated codon (Decipher, PMID: 10477533). (SP) 0703 - Other synonymous splice variants comparable to the one identified in this case have moderate previous evidence for pathogenicity. Alternative changes at the same nucleotide position (c.1032G>C, c.1032G>T) have been reported as pathogenic, likely pathogenic and in a family with LQTS (ClinVar, PMID: 10477533). (SP) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been reported many times as pathogenic and in multiple families with LQTS (ClinVar, PMID: 21810471, PMID: 10477533). (SP) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -
NM_000218.3(KCNQ1):c.1032G>A is a synonymous variant (p.Ala344=) predicted to affect KCNQ1 mRNA splicing. The computational splicing predictor SpliceAI gives scores of 0.49 for donor gain and 0.38 for donor loss, which are higher than the ClinGen Potassium Channel Arrhythmia VCEP PP3 threshold of greater than or equal to 0.2 and predict that the variant disrupts KCNQ1 splicing (PP3). The variant is observed at an extremely low frequency in the population with a maximum allele frequency (gnomAD 4.1.0) of 0.000001701, with 2 in 1,175,668 individuals of European (non-Finnish) ancestry (PM2_Supporting). Functional studies have been performed on this variant and meet criteria with demonstrated deleterious effects on electrophysiology and RNA metabolism (PS3, PMID: 29857160, 10477533, 17292394). There are 23 reported probands in the literature with a clinical diagnosis of Long QT syndrome (PS4; PMID: 26118460, PMID: 21810471, PMID: 9654228, PMID: 29497013, PMID: 17292394). An additional case reports provides specific details that are highly specific for a diagnosis of Long QT syndrome in an individual with the variant who had a significantly prolonged QTc at rest and exercise-triggered events (PP4, PMID: 21810471). In summary, this variant meets the criteria to be classified as pathogenic for long QT syndrome 1 based on the ACMG/AMP criteria applied, as specified by the ClinGen Potassium Channel Arrhythmia VCEP: PS3, PS4, PM2_Supporting, PP3, and PP4. (VCEP specifications version 1.0.0; date of approval 03/04/2025). -
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not provided Pathogenic:3
Not observed at a significant frequency in large population cohorts (Lek et al., 2016); A different nucleotide change at the same position (c.1032 G>C, A344A) has also been reported to affect splicing and was found to segregate with a LQTS phenotype in a multi-generation family (Murray et al., 1999); Reported in ClinVar as pathogenic (ClinVar Variant ID# 3135; Landrum et al., 2016); This variant is associated with the following publications: (PMID: 21810471, 29857160, 9570196, 26318259, 10973849, 19716085, 29497013, 10477533, 22629021, 9654228, 26118460, 29255176, 27485560, 28438721, 17292394, 31737537, 31589614) -
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The KCNQ1 c.1032G>A; p.Ala344= variant (rs1800171) is reported in the literature in individuals and families affected with long QT syndrome (Gao 2012, Kanters 1998, Tsuji 2007, Tsuji-Wakisaka 2011). This variant is also reported in ClinVar (Variation ID: 3135). It is only found on one allele in the Genome Aggregation Database, indicating it is not a common polymorphism. This is a synonymous variant in the last nucleotide of exon 7, and mRNA assays have shown this variant causes exon skipping (Tsuji 2007, Tsuji-Wakisaka 2011). Based on available information, this variant is considered to be pathogenic. References: Gao Y et al. Genotype-phenotype analysis of three Chinese families with Jervell and Lange-Nielsen syndrome. J Cardiovasc Dis Res. 2012 Apr;3(2):67-75. PMID: 22629021. Kanters JK et al. Novel donor splice site mutation in the KVLQT1 gene is associated with long QT syndrome. J Cardiovasc Electrophysiol. 1998 Jun;9(6):620-4. PMID: 9654228. Tsuji K et al. Mechanistic basis for the pathogenesis of long QT syndrome associated with a common splicing mutation in KCNQ1 gene. J Mol Cell Cardiol. 2007 Mar;42(3):662-9. PMID: 17292394. Tsuji-Wakisaka K et al. Identification and functional characterization of KCNQ1 mutations around the exon 7-intron 7 junction affecting the splicing process. Biochim Biophys Acta. 2011 Nov;1812(11):1452-9. PMID: 21810471. -
Long QT syndrome Pathogenic:3
Variant summary: KCNQ1 c.1032G>A (p.Ala344Ala) alters a non-conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: Two predict the variant abolishes a 5' splicing donor site. Three predict the variant weakens a 5' donor site. At least two publications reported experimental evidence that this variant affects mRNA splicing (Murray 1999, Tsuji-Wakisaka 2011), causing a partial exon skipping, decreasing the wild type mRNA level to about 55% (Tsuji-Wakisaka 2011). The variant allele was found at a frequency of 4e-06 in 251186 control chromosomes (gnomAD). c.1032G>A has been reported in the literature in multiple individuals affected with Long QT Syndrome (Kanters 1998, Li 1998, Murray 1999, Tsuji-Wakisaka 2011), and in two large families the variant co-segregated with the disease (Li 1998, Murray 1999). These data indicate that the variant is very likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function, and demonstrated significant reduction in currents compared to control (Tsuji-Wakisaka 2011). Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
This sequence change affects codon 344 of the KCNQ1 mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the KCNQ1 protein. RNA analysis indicates that this variant induces altered splicing and likely results in a shortened protein product. This variant is present in population databases (rs1800171, gnomAD 0.0009%). This variant has been observed in individuals with Jervell and Lange-Nielsen syndrome and/or long QT syndrome (PMID: 9654228, 10973849, 21810471, 22629021). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 3135). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant results in skipping of exon 7, but is expected to preserve the integrity of the reading-frame (PMID: 21810471). For these reasons, this variant has been classified as Pathogenic. -
The c.1032G>A (p.Ala344=) variant in the KCNQ1 gene has been reported in multiple individuals with long QT syndrome and Jervell and Lange-Nielsen syndrome (PMID: 17292394, 9654228, 10973849, 29857160, 32893267). RNA studies have shown that this variant causes exon 7 skipping (PMID: 21810471). This variant has been demonstrated to disrupt protein function (PMID: 17292394). This variant has been reported in ClinVar as pathogenic (ID: 3135). The overall frequency of this variant in the population database (gnomAD) is 1/251186 chromosomes. Based on this evidence, the c.1032G>A (p.Ala344=) variant in the KCNQ1 gene has been classified as pathogenic. -
Long QT syndrome 2 Pathogenic:1
ACMG score pathogenic -
Beckwith-Wiedemann syndrome Pathogenic:1
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Congenital long QT syndrome Pathogenic:1
The p.Ala344Ala variant in KCNQ1 has been reported in >20 heterozygous individuals with Long QT syndrome (LQTS) and in one compound heterozygous individual with Jervell and Lange-Nielsen syndrome (JLNS). It segregated with LQTS in > 10 relatives from multiple families (Kanters 1998, Struijk 2006, Tsuji 2007, Gao 2012, Itoh 2015, Vyas 2016, Robyns 2017). This variant has also been reported in ClinVar (Variation ID: 3135) and has been identified in 1/111614 European chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org/; dbSNP rs1800171). This variant is located at the last base of exon 7, which is part of the 5’ splice region. Computational tools and functional studies using patient mRNAs suggest that the p.Ala344ala variant impacts splicing, resulting mainly in the skipping of exon 7 but other aberrant mRNA transcripts were also reported (Wuriyanghai 2018, Tsuji 2007). In summary, this variant meets criteria to be classified as pathogenic for LQTS in an autosomal dominant manner based upon presence in multiple affected individuals, segregation studies, predicted impact to the protein, and functional studies. ACMG/AMP criteria applied: PS4, PP1_Strong, PM4, PS3_Moderate, PM2. -
Cardiovascular phenotype Pathogenic:1
The c.1032G>A pathogenic mutation (also known as p.A344A) is located in coding exon 7 of the KCNQ1 gene. This variant results from a G to A substitution at nucleotide position 1032. This nucleotide substitution does not change the amino acid at codon 344. However, this change occurs in the last base pair of coding exon 7, which makes it likely to have some effect on normal mRNA splicing. This alteration has been reported in multiple families with long QT syndrome (LQTS) and Jervell and Lange-Nielsen syndrome, including at least one reported de novo case of LQTS (Kanters JK et al. J. Cardiovasc. Electrophysiol., 1998 Jun;9:620-4; Murray A et al. Circulation, 1999 Sep;100:1077-84; Tsuji-Wakisaka K et al. Biochim. Biophys. Acta, 2011 Nov;1812:1452-9; Gao Y et al. J Cardiovasc Dis Res, 2012 Apr;3:67-75). RNA studies have demonstrated that this alteration leads to exon skipping with the loss of exon 7 as the most frequently observed effect (Murray A et al. Circulation, 1999 Sep;100:1077-84; Tsuji-Wakisaka K et al. Biochim. Biophys. Acta, 2011 Nov;1812:1452-9). In addition, in vitro functional studies have shown significant suppression of potassium channel currents (Tsuji-Wakisaka K et al. Biochim. Biophys. Acta, 2011 Nov;1812:1452-9). This nucleotide position is not well conserved in available vertebrate species. Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at