2-178681080-T-G

Variant names:

• chr2-178681080-T-G
• rs926306750
• NM_001267550.2:c.33339A>C

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_001267550.2(TTN):​c.33339A>C​(p.Lys11113Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000691 in 1,447,812 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. K11113K) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 3.54
• Publications: 0 publications found

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

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. Scorers claiming Uncertain: max_spliceai. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.33339A>C	p.Lys11113Asn	missense_variant	Exon 138 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.33339A>C	p.Lys11113Asn	missense_variant	Exon 138 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.91e-7 AC: 1 AN: 1447812 Hom.: 0 Cov.: 29 AF XY: 0.00 AC XY: 0 AN XY: 719632

African (AFR) AF: 0.00 AC: 0 AN: 32522

American (AMR) AF: 0.00 AC: 0 AN: 41416

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25792

East Asian (EAS) AF: 0.00 AC: 0 AN: 39550

South Asian (SAS) AF: 0.00 AC: 0 AN: 82282

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53202

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5736

European-Non Finnish (NFE) AF: 9.03e-7 AC: 1 AN: 1107420

Other (OTH) AF: 0.00 AC: 0 AN: 59892

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.62
BayesDel_addAF	Benign	-0.090	T
BayesDel_noAF	Benign	-0.37
CADD	Pathogenic	28
DANN	Uncertain	0.98
Eigen	Uncertain	0.63
Eigen_PC	Uncertain	0.62
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Benign	0.51	T;T;.;T
M_CAP	Uncertain	0.11	D
MetaRNN	Benign	0.34	T;T;T;T
MetaSVM	Uncertain	0.044	D
PhyloP100		3.5
PrimateAI	Benign	0.48	T
PROVEAN	Uncertain	-2.8	D;.;.;.
REVEL	Uncertain	0.32
Sift	Pathogenic	0.0	D;.;.;.
Polyphen		1.0	.;.;D;D
Vest4		0.33
MutPred		0.45		.;.;Loss of methylation at K10796 (P = 0.0017);Loss of methylation at K10796 (P = 0.0017);
MVP		0.33
MPC		0.49
ClinPred		0.87	D
GERP RS		5.9
Mutation Taster		=28/72	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.41		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.41		Position offset: 21

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

Other links and lift over

dbSNP: rs926306750; hg19: chr2-179545807;