3-52451288-T-G

Position:

• chr3-52451288-T-G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM1 PM2 BP4

The NM_003280.3(TNNC1):​c.473A>C​(p.Lys158Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. K158R) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TNNC1 NM_003280.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.33

Genes affected

TNNC1 (HGNC:11943): (troponin C1, slow skeletal and cardiac type) Troponin is a central regulatory protein of striated muscle contraction, and together with tropomyosin, is located on the actin filament. Troponin consists of 3 subunits: TnI, which is the inhibitor of actomyosin ATPase; TnT, which contains the binding site for tropomyosin; and TnC, the protein encoded by this gene. The binding of calcium to TnC abolishes the inhibitory action of TnI, thus allowing the interaction of actin with myosin, the hydrolysis of ATP, and the generation of tension. Mutations in this gene are associated with cardiomyopathy dilated type 1Z. [provided by RefSeq, Oct 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_003280.3
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.35469404).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TNNC1	NM_003280.3	c.473A>C	p.Lys158Thr	missense_variant	6/6	ENST00000232975.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TNNC1	ENST00000232975.8	c.473A>C	p.Lys158Thr	missense_variant	6/6	1	NM_003280.3	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Dilated cardiomyopathy 1Z;C2750472:Hypertrophic cardiomyopathy 13 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 22, 2017

In summary, this variant has uncertain impact on TNNC1 function. The available evidence is currently insufficient to determine its role in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with a TNNC1-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change replaces lysine with threonine at codon 158 of the TNNC1 protein (p.Lys158Thr). The lysine residue is moderately conserved and there is a moderate physicochemical difference between lysine and threonine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.44
BayesDel_addAF	Uncertain	0.13	D
BayesDel_noAF	Uncertain	-0.050
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Benign	0.39	T
Eigen	Benign	0.13
Eigen_PC	Benign	0.20
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.92	D
M_CAP	Uncertain	0.22	D
MetaRNN	Benign	0.35	T
MetaSVM	Uncertain	0.23	D
MutationAssessor	Benign	1.0	L
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.68	T
PROVEAN	Benign	0.080	N
REVEL	Uncertain	0.46
Sift	Benign	0.33	T
Sift4G	Benign	0.36	T
Polyphen		0.94	P
Vest4		0.16
MutPred		0.44		Loss of ubiquitination at K158 (P = 0.0244);
MVP		0.71
MPC		0.76
ClinPred		0.84	D
GERP RS		4.0
Varity_R		0.45
gMVP		0.79

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1553651622; hg19: chr3-52485304;