rs397516848
Variant summary
Our verdict is Likely benign. The variant received -1 ACMG points: 3P and 4B. PM1PP2BS2
The NM_003280.3(TNNC1):c.442A>G(p.Ile148Val) variant causes a missense change. The variant allele was found at a frequency of 0.000013 in 1,614,028 control chromosomes in the GnomAD database, including 1 homozygotes. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. I148I) has been classified as Likely benign.
Frequency
Consequence
NM_003280.3 missense
Scores
Clinical Significance
Conservation
Publications
- dilated cardiomyopathyInheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
- dilated cardiomyopathy 1ZInheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae)
- hypertrophic cardiomyopathyInheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
- hypertrophic cardiomyopathy 13Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), PanelApp Australia, G2P
- familial isolated dilated cardiomyopathyInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- arrhythmogenic right ventricular cardiomyopathyInheritance: AD Classification: NO_KNOWN Submitted by: ClinGen
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ACMG classification
Our verdict: Likely_benign. The variant received -1 ACMG points.
Transcripts
RefSeq
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | TSL | MANE | Protein | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|---|
| TNNC1 | ENST00000232975.8 | c.442A>G | p.Ile148Val | missense_variant | Exon 5 of 6 | 1 | NM_003280.3 | ENSP00000232975.3 | ||
| TNNC1 | ENST00000496590.1 | c.*12A>G | downstream_gene_variant | 2 | ENSP00000420596.1 | |||||
| TNNC1 | ENST00000461086.1 | n.*36A>G | downstream_gene_variant | 2 |
Frequencies
GnomAD3 genomes AF: 0.0000131 AC: 2AN: 152164Hom.: 0 Cov.: 33 show subpopulations
GnomAD2 exomes AF: 0.00000797 AC: 2AN: 250838 AF XY: 0.0000147 show subpopulations
GnomAD4 exome AF: 0.0000130 AC: 19AN: 1461864Hom.: 1 Cov.: 31 AF XY: 0.0000110 AC XY: 8AN XY: 727230 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000131 AC: 2AN: 152164Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2AN XY: 74338 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
not specified Uncertain:2
Variant summary: TNNC1 c.442A>G (p.Ile148Val) results in a conservative amino acid change located in the EF-hand domain (IPR002048) of the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 8e-06 in 250838 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.442A>G has been reported in the literature in individuals affected with Cardiomyopathy and SUD (e.g. Hershberger_2010, Pinto_2011, Ng_2013, Pugh_2014, Dewar_2017). These reports do not provide unequivocal conclusions about association of the variant with Cardiomyopathy. A co-occurrence with a likely pathogenic variant has been reported (DSP c.2848_2849insA, p.Ile950AsnfsX3; Pugh_2014). Experimental evidence evaluating an impact on protein function demonstrated pig skinned fibers reconstituted with the variant and incubated with PKA, to have a reduced effect of PKA phosphorylation on myofilament Ca2+ desensitization compared with WT. Nevertheless, the variant was similar to WT in fully activating or inhibiting the actomyosin ATPase activity in the presence and absence of Ca2+, while it did not affect the maximal force recovery in the presence or absence of PKA compared with WT (Pinto_2011). These data do not allow convincing conclusions about the variant effect. Two ClinVar submitters (evaluation after 2014) cite the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -
The Ile148Val variant in TNNC1 has been identified in 1 individual with DCM and was absent from 492 control chromosomes (Hershberger 2010). Studies showed that this variant exhibited decreased calcium sensitivity and altered response to PKA phosphorylation, but these in vitro assays may not accurately represent biologi cal function (Pinto 2011). Computational analyses (biochemical amino acid proper ties, conservation,AlignGVGD, and SIFT) suggest that the Ile148Val variant may n ot impact the protein, though this information is not predictive enough to rule out pathogenicity. In summary, the available information for this variant is con flicting and additional information is needed to fully assess its clinical signi ficance. -
Dilated cardiomyopathy 1Z;C2750472:Hypertrophic cardiomyopathy 13 Uncertain:1
This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 148 of the TNNC1 protein (p.Ile148Val). This variant is present in population databases (rs397516848, gnomAD 0.003%). This missense change has been observed in individual(s) with clinical features of dilated cardiomyopathy (PMID: 20215591, 24503780, 27532257, 28807990, 37652022). ClinVar contains an entry for this variant (Variation ID: 44682). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. Experimental studies have shown that this missense change affects TNNC1 function (PMID: 21832052). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -
Primary dilated cardiomyopathy Uncertain:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at