rs527924868

Positions:

• chr2-178756410-A-G

Variant summary

Our verdict is Benign. Variant got -8 ACMG points: 1P and 9B. PP2 BP4_Strong BP6 BS2

The NM_001267550.2(TTN):​c.11066T>C​(p.Ile3689Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000954 in 1,613,798 control chromosomes in the GnomAD database, including 3 homozygotes. In-silico tool predicts a benign outcome for this variant. 13/16 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 0.00011 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000094 (3 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2 B:3
• Conservation: PhyloP100: 1.20

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]

ACMG classification

Verdict is Benign. Variant got -8 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=0.0072597563).
• BP6: Variant 2-178756410-A-G is Benign according to our data. Variant chr2-178756410-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 535111.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, Uncertain_significance=2}. Variant chr2-178756410-A-G is described in Lovd as [Likely_benign].
• BS2: High Homozygotes in GnomAdExome4 at 3 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2	c.11066T>C	p.Ile3689Thr	missense_variant	46/363	ENST00000589042.5	NP_001254479.2
TTN	NM_133379.5	c.10303+2574T>C		intron_variant		ENST00000360870.10	NP_596870.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.11066T>C	p.Ile3689Thr	missense_variant	46/363	5	NM_001267550.2	ENSP00000467141	P1
TTN	ENST00000360870.10	c.10303+2574T>C		intron_variant		5	NM_133379.5	ENSP00000354117
TTN-AS1	ENST00000659121.1	n.1280+88A>G		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.000112 AC: 17 AN: 152160 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000724

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00228

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000441

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000165 AC: 41 AN: 248610 Hom.: 0 AF XY: 0.000200 AC XY: 27 AN XY: 134864

Gnomad AFR exome AF: 0.0000646

Gnomad AMR exome AF: 0.0000290

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00118

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000266

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000937 AC: 137 AN: 1461520 Hom.: 3 Cov.: 33 AF XY: 0.000116 AC XY: 84 AN XY: 727050

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00122

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000216

Gnomad4 OTH exome AF: 0.0000663

GnomAD4 genome AF: 0.000112 AC: 17 AN: 152278 Hom.: 0 Cov.: 32 AF XY: 0.000175 AC XY: 13 AN XY: 74460

Gnomad4 AFR AF: 0.0000722

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00228

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000441

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000754 Hom.: 0

Bravo AF: 0.0000264

ExAC AF: 0.000190 AC: 23

EpiCase AF: 0.0000545

EpiControl AF: 0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2 Benign:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:1 Benign:2

Uncertain significance, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Mar 01, 2024	- -
Likely benign, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -
Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Nov 12, 2022

Variant summary: TTN c.10303+2574T>C is located at a position not widely known to affect splicing. 4/4 computational tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 0.00016 in 248610 control chromosomes (gnomAD), predominantly at a frequency of 0.0012 within the South Asian subpopulation in the gnomAD database. To our knowledge, no occurrence of c.10303+2574T>C in individuals affected with Limb-Girdle Muscular Dystrophy, Type 2J and no experimental evidence demonstrating its impact on protein function have been reported. One ClinVar submitter has assessed the variant since 2014: the variant was classified as likely benign. Based on the evidence outlined above, the variant was classified as VUS-possibly benign. -

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

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 28, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.56	T
BayesDel_noAF	Benign	-0.62
CADD	Benign	13
DANN	Benign	0.71
Eigen	Benign	-0.71
Eigen_PC	Benign	-0.72
FATHMM_MKL	Benign	0.043	N
LIST_S2	Benign	0.40	T;T
M_CAP	Benign	0.012	T
MetaRNN	Benign	0.0073	T;T
MetaSVM	Benign	-0.93	T
MutationTaster	Benign	1.0	N;N;N;N;N;N;N
PROVEAN	Benign	-0.23	.;N
REVEL	Benign	0.14
Sift	Benign	0.38	.;T
Vest4		0.18
MutPred		0.53		.;Loss of stability (P = 0.0012);
MVP		0.40
MPC		0.11
ClinPred		0.020	T
GERP RS		1.3

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: rs527924868; hg19: chr2-179621137;