2-178659037-A-G

Position:

• chr2-178659037-A-G

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 1P and 2B. PP2 BP4_Moderate

The NM_001267550.2(TTN):​c.37421T>C​(p.Ile12474Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. In-silico tool predicts a benign outcome for this variant. 15/18 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.00013 (0 hom., cov: 12)
  • Exomes 𝑓: 0.00015 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:4 B:1 O:1
• Conservation: PhyloP100: 1.08

Genes affected

TTN (HGNC:12403): (titin) This gene encodes a large abundant protein of striated muscle. The product of this gene is divided into two regions, a N-terminal I-band and a C-terminal A-band. The I-band, which is the elastic part of the molecule, contains two regions of tandem immunoglobulin domains on either side of a PEVK region that is rich in proline, glutamate, valine and lysine. The A-band, which is thought to act as a protein-ruler, contains a mixture of immunoglobulin and fibronectin repeats, and possesses kinase activity. An N-terminal Z-disc region and a C-terminal M-line region bind to the Z-line and M-line of the sarcomere, respectively, so that a single titin molecule spans half the length of a sarcomere. Titin also contains binding sites for muscle associated proteins so it serves as an adhesion template for the assembly of contractile machinery in muscle cells. It has also been identified as a structural protein for chromosomes. Alternative splicing of this gene results in multiple transcript variants. Considerable variability exists in the I-band, the M-line and the Z-disc regions of titin. Variability in the I-band region contributes to the differences in elasticity of different titin isoforms and, therefore, to the differences in elasticity of different muscle types. Mutations in this gene are associated with familial hypertrophic cardiomyopathy 9, and autoantibodies to titin are produced in patients with the autoimmune disease scleroderma. [provided by RefSeq, Feb 2012]

TTN-AS1 (HGNC:44124): (TTN antisense RNA 1) This gene encodes a non-coding RNA transcribed from the opposite strand to the titin gene. [provided by RefSeq, Aug 2016]

LOC124906100 (HGNC:):

ACMG classification

Verdict is Likely_benign. Variant got -1 ACMG points.

• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TTN. . Gene score misZ -1.1021 (greater than the threshold 3.09). Trascript score misZ 6.9794 (greater than threshold 3.09). GenCC has associacion of gene with dilated cardiomyopathy, tibial muscular dystrophy, early-onset myopathy with fatal cardiomyopathy, autosomal recessive centronuclear myopathy, hypertrophic cardiomyopathy, hypertrophic cardiomyopathy 9, TTN-related myopathy, dilated cardiomyopathy 1G, arrhythmogenic right ventricular cardiomyopathy, myopathy, myofibrillar, 9, with early respiratory failure, familial isolated dilated cardiomyopathy, childhood-onset progressive contractures-limb-girdle weakness-muscle dystrophy syndrome, autosomal recessive limb-girdle muscular dystrophy type 2J.
• BP4: Computational evidence support a benign effect (MetaRNN=0.14793402).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2	c.37421T>C	p.Ile12474Thr	missense_variant	182/363	ENST00000589042.5	NP_001254479.2
LOC124906100	XR_007087318.1	n.2185+14536A>G		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.37421T>C	p.Ile12474Thr	missense_variant	182/363	5	NM_001267550.2	ENSP00000467141	P1
TTN-AS1	ENST00000659121.1	n.502+61356A>G		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.00 AC: 14 AN: 105270 Hom.: 0 Cov.: 12 FAILED QC

Gnomad AFR AF: 0.0000678

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000203

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000186

Gnomad OTH AF: 0.000753

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.000146 AC: 119 AN: 814744 Hom.: 0 Cov.: 11 AF XY: 0.000146 AC XY: 60 AN XY: 411654

Gnomad4 AFR exome AF: 0.0000974

Gnomad4 AMR exome AF: 0.000320

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000298

Gnomad4 SAS exome AF: 0.0000183

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.000158

Gnomad4 OTH exome AF: 0.000286

GnomAD4 genome Data not reliable, filtered out with message: AS_VQSR AF: 0.000133 AC: 14 AN: 105376 Hom.: 0 Cov.: 12 AF XY: 0.000100 AC XY: 5 AN XY: 49876

Gnomad4 AFR AF: 0.0000676

Gnomad4 AMR AF: 0.000202

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000186

Gnomad4 OTH AF: 0.000742

Alfa AF: 0.000184 Hom.: 0

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:4 Benign:1 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Feb 04, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Dec 02, 2016	- -

not specified Benign:1 Other:1

Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Jan 03, 2018	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
not provided, no classification provided	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Jan 30, 2013	- -

TTN-related disorder Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

May 22, 2024

The TTN c.37421T>C variant is predicted to result in the amino acid substitution p.Ile12474Thr. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.047% of alleles in individuals of Latino descent in gnomAD. This variant falls within a highly paralogous region. Allele frequency data should be interpreted with caution. At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 27, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.30
BayesDel_addAF	Benign	-0.11	T
BayesDel_noAF	Benign	-0.40
CADD	Benign	12
DANN	Benign	0.77
Eigen	Benign	-0.45
Eigen_PC	Benign	-0.53
FATHMM_MKL	Benign	0.15	N
LIST_S2	Benign	0.71	T;T;D
M_CAP	Benign	0.030	D
MetaRNN	Benign	0.15	T;T;T
MetaSVM	Benign	-0.58	T
MutationTaster	Benign	1.0	D;D;D;D;N;N
PrimateAI	Benign	0.45	T
PROVEAN	Benign	-1.8	N;.;.
REVEL	Benign	0.12
Sift	Benign	0.33	T;.;.
Polyphen		0.025	.;.;B
Vest4		0.20
MutPred		0.37		.;.;Gain of phosphorylation at I11497 (P = 0.0022);
MVP		0.47
MPC		0.26
ClinPred		0.021	T
GERP RS		4.1

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs72650057; hg19: chr2-179523764;