ClinVar Miner

Submissions for variant NM_172056.2(KCNH2):c.1838C>T (p.Thr613Met) (rs199473524)

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Total submissions: 7
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Submitter RCV SCV Clinical significance Condition Last evaluated Review status Method Comment
Ambry Genetics RCV000244892 SCV000320544 pathogenic Cardiovascular phenotype 2015-10-27 criteria provided, single submitter clinical testing Deficient protein function in appropriate functional assay(s);Well-characterized mutation at same position;Detected in individual satisfying established diagnostic critera for classic disease without a clear mutation
GeneDx RCV000223761 SCV000490549 pathogenic not provided 2015-10-09 criteria provided, single submitter clinical testing The pathogenic T613M variant in the KCNH2 gene has been reported multiple times in association with LQTS and was absent from >2,000 alleles from control individuals of different ethnic backgrounds in these studies (Jongbloed et al., 1999; Laitinen et al., 2000; Splawski et al., 2000; Simpson et al., 2009; Lupoglazoff et al., 2004; Van Langen et al., 2003; Choi et al., 2004). The T613M variant was first identified in a Dutch individual with LQTS, and subsequently identified in several other individuals with LQTS, with T613M occurring as a de novo variant in at least two instances (Jongbloed et al., 1999; Laitinen et al., 2000; Splawski et al., 2000; Simpson et al., 2009; Lupoglazoff et al., 2004; Van Langen et al., 2003; Choi et al., 2004). The clinical variability associated with the pathogenic T613M variant was further described after this variant was detected in three infants, one of whom was diagnosed with fetal ventricular tachycardia (Simpson et al., 2009; Lupoglazoff et al., 2004). Additionally, T613M has been observed in multiple other unrelated individuals tested for LQTS at GeneDx. Furthermore, T613M was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. The T613M variant is a non-conservative amino acid substitution as these residues differ in polarity, charge, size and/or other properties and is more likely to impact secondary structure. The T613 residue is highly conserved across species (Jongbloed et al., 1999). The T613M variant is located in the pore of the KCNH2 protein, where several pathogenic variants associated with LQTS have also been reported, and variants in this region are expected to disrupt potassium transport (Splawski et al., 2000). Moreover, subsequent functional studies show that T613M does result in deficient protein trafficking (Anderson et al., 2014). In summary, T613M in the KCNH2 gene is interpreted as a pathogenic variant.
Invitae RCV000527495 SCV000627442 pathogenic Long QT syndrome 2019-11-25 criteria provided, single submitter clinical testing This sequence change replaces threonine with methionine at codon 613 of the KCNH2 protein (p.Thr613Met). The threonine residue is highly conserved and there is a moderate physicochemical difference between threonine and methionine. This variant is not present in population databases (ExAC no frequency). This variant has been reported in several individuals affected with long QT syndrome, being described as de novo in two of these cases (PMID: 10220144 , 10862094, 10973849 , 14720170, 14998624 , 18441445 , 19731233, 22402334, 22949429). ClinVar contains an entry for this variant (Variation ID: 67292). This variant identified in the KCNH2 gene is located in the pore region of the resulting protein (PMID: 19841300, 25348405). For more information about the location of this variant, please visit Experimental studies have shown that this missense change causes a defect in protein trafficking, exerting a dominant negative effect on protein function when co-expressed with the WT protein (PMID: 11524404, 25417810). For these reasons, this variant has been classified as Pathogenic.
Integrated Genetics/Laboratory Corporation of America RCV000244892 SCV000696021 pathogenic Cardiovascular phenotype 2016-10-31 criteria provided, single submitter clinical testing Variant summary: The c.1838C>T (p.Thr613Met) in KCNH2 gene is a missense change that alters a highly conserved nucleotide and 5/5 in silico tools predict neutral outcome. The variant located in the pore region and several alterations of neighboring codons have been identified in LQTS pts. The variant was not observed in the large cohort of the ExAC project. The variant has been reported in multiple affected individuals with confirmed dx of LQTS and has it been cited as Likely Pathogenic/Pathogenic by several reputable databases/clinical laboratories. Taking together, the variant of interest was classified as Pathogenic.
Centre for Mendelian Genomics,University Medical Centre Ljubljana RCV001196417 SCV001367025 pathogenic Ventricular tachycardia 2019-09-11 criteria provided, single submitter clinical testing This variant was classified as: Uncertain significance. The available evidence on this varinat's pathogenicity is insufficient or conflicting. The following ACMG criteria were applied in classifying this variant: PP3,PP5. This variant was detected in heterozygous state.
Cardiovascular Biomedical Research Unit,Royal Brompton & Harefield NHS Foundation Trust RCV000058009 SCV000089529 not provided Congenital long QT syndrome no assertion provided literature only This variant has been reported as associated with Long QT syndrome in the following publications (PMID:10220144;PMID:10862094;PMID:10973849;PMID:11222472;PMID:11854117;PMID:12566525;PMID:14998624;PMID:15466642;PMID:15840476;PMID:16379539;PMID:16922724;PMID:17224687;PMID:18441445;PMID:19716085;PMID:19731233;PMID:19841300;PMID:22402334). This is a literature report, and does not necessarily reflect the clinical interpretation of the Imperial College / Royal Brompton Cardiovascular Genetics laboratory.
Stanford Center for Inherited Cardiovascular Disease, Stanford University RCV000223761 SCV000280121 likely pathogenic not provided 2015-06-02 no assertion criteria provided clinical testing Note this variant was found in clinical genetic testing performed by one or more labs who may also submit to ClinVar. Thus any internal case data may overlap with the internal case data of other labs. The interpretation reviewed below is that of the Stanford Center for Inherited Cardiovascular Disease. KCNH2 p.Thr613Met Based on the evidence provided below, we too consider this variant likely disease causing. This variant has been reported in at least 12 unrelated subjects with LQTS in the scientific literature and in arrhythmia databases as of October 2013. Some weak segregation data is presented in two of these studies and another group presented some functional data in support of a dominant negative effect of this mutation. This is a non-conservative amino acid substitution in which a polar threonine is replaced by a nonpolar methionine. In silico analysis with Polyphen predicts the variant to be probably damaging; Mutation Taster predicts it to be damaging in 4 of 4 transcripts; and SIFT predicts it to be deleterious. The threonine at codon 613 is highly conserved across species, as are neighboring amino acids. Several nearby variants have been reported in association with disease in the literature: Y611H, V612L, and A614V (note, none of these have been reviewed by SCICD team). This variant is located in exon 7 within the pore region of KCNH2. Mutations in KCNH2 cause long QT syndrome type 2 (LQT2). Thr613Met is currently present in HGMD as a disease-causing mutation. Jongbloed et al. (1999) screened 24 Dutch index patients and families with LQTS for mutations in KCNQ1 and KCNH2. They identified this variant in a patient whose father died during sleep and whose brother died before age 40 (trigger of syncope = acoustic). The authors note that this variant was novel at the time of the study. The authors also note that this missense mutation is situated in a CpG sequence, which are known as mutation-sensitive due to potential deamination of 5-methylcytosine at the CpG dinucleotides. The variant was absent from 55 control individuals in this study. This variant was also identified by Laitinen et al. (2000): They screened 39 Finnish LQTS patients, and identified the Thr613Met variant in one proband with LQTS. Notably, it was judged to be a de novo mutation, as it was absent from both parents. Mean QTc of this patient was 536 msec. Splawski et al. (2000) screened 262 unrelated individuals of North American and European ancestry with LQTS for mutations in 5 defined genes. They identified Thr613Met in 3 families with LQTS. It was not present in over 200 control individuals. Lupoglazoff et al. (2001) studied the T-wave morphology of 133 carriers of mutations in KCNQ1 and KCNH2 and also of 100 control individuals. Thr613Met was one of the KCNH2 variants that was present in the cohort but the authors do not specify how many unrelated individuals carried this particular variant. Moss et al. (2002) studied 201 subjects with genetically confirmed KCNH2 mutations derived from 51 LQT2 families from the International LQTS registry. This particular variant was identified in 1 subject. Simpson et al. (2009) identified this variant in a fetus who presented at 30 weeks gestation with VT at a rate of 220 beats/min and fetal hydrops. Despite rapid control of the arrhythmia the fetus developed severe periventricular leukomalacia before birth for which a poor neurological prognosis was given. The baby was delivered preterm at 32 weeks' gestation and died on the sixth day after birth. Long QT syndrome was identified postnatally on the electrocardiogram, and it was confirmed by genetic testing which showed a mutation in the KCNH2 gene (p.Thr613Met). The authors stated that the parents tested negative for the variant. Lupoglazoff et al. (2004) analyzed 23 neonate probands with LQTS and 2:1 AV block. They identified this variant by maternal transmission in 2 unrelated probands with LQTS and 2:1 AV block: one who was diagnosed after fetal bradycardia and torsades de pointes, with a QTc of 580; and another who presented with neonatal bradycardia and a QTc of 520. Shim et al. (2005): Studied 7 infants with LQTS. One infant presented at delivery with 2:1 AV block and was identified as having T613M in KCNH2 and P2005A in SCN5A (the father was a carrier of the P2005A variant, and the mother carried the T613M variant and had an ICD). Huang et al. (2001) sought to characterize the physiological consequences of three different LQTS-associated missense mutations, including Thr613Met, that are located in the pore helix of KCNH2. Mutant HERG subunits were heterologously expressed in Xenopus oocytes alone or in combination with wildtype HERG subunits. When expressed alone, T613M did not induce detectable currents. Coexpression of mutant and wildtype HERG subunits caused a dominant negative effect. This mutation reportedly prevented normal trafficking of the HERG protein to the surface membrane, as shown by the decrease in cell-surface chemiluminescence of HA-tagged mutant subunits compared with HA-tagged WT HERG subunits. The direction of the shifts in gating caused by T613Mwould be expected to cause a decrease in current beyond that resulting from a dominant negative induced suppression of channel function. In total, this variant is absent from ~6,755 control individuals (including ~6500 individuals of European and African American descent from the NHLBI ESP; 55 control individuals from Jongbloed et al. 1999; 200 control individuals from Splawski et al. 2000). This variant has the following legacy names: T273M; T613M; T517M.

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