chr2-178558217-A-G

Variant names:

• chr2-178558217-A-G
• rs143975327
• NM_001267550.2:c.87137T>C

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_001267550.2(TTN):​c.87137T>C​(p.Met29046Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000311 in 1,606,828 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. M29046R) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.32
• Publications: 3 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]

ENSG00000279598 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001267550.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.87137T>C	p.Met29046Thr	missense	Exon 328 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.82214T>C	p.Met27405Thr	missense	Exon 278 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.79433T>C	p.Met26478Thr	missense	Exon 277 of 312	NP_596869.4	Q8WZ42-11

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.87137T>C	p.Met29046Thr	missense	Exon 328 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.86981T>C	p.Met28994Thr	missense	Exon 326 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.86861T>C	p.Met28954Thr	missense	Exon 326 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152250 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00000417 AC: 1 AN: 239802 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000911

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000275 AC: 4 AN: 1454578 Hom.: 0 Cov.: 32 AF XY: 0.00000277 AC XY: 2 AN XY: 723032

African (AFR) AF: 0.00 AC: 0 AN: 32958

American (AMR) AF: 0.00 AC: 0 AN: 42816

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25998

East Asian (EAS) AF: 0.00 AC: 0 AN: 39628

South Asian (SAS) AF: 0.00 AC: 0 AN: 83740

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53256

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5748

European-Non Finnish (NFE) AF: 0.00000360 AC: 4 AN: 1110316

Other (OTH) AF: 0.00 AC: 0 AN: 60118

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152250 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74374

African (AFR) AF: 0.00 AC: 0 AN: 41470

American (AMR) AF: 0.00 AC: 0 AN: 15284

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5194

South Asian (SAS) AF: 0.00 AC: 0 AN: 4836

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10626

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68050

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.00 Hom.: 1

Bravo AF: 0.00000378

ExAC AF: 0.00000828 AC: 1

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
-	1	-	Cardiomyopathy (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.39
BayesDel_addAF	Uncertain	0.053	T
BayesDel_noAF	Benign	-0.16
CADD	Benign	21
DANN	Benign	0.89
Eigen	Pathogenic	0.72
Eigen_PC	Pathogenic	0.76
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.88	D
M_CAP	Benign	0.045	D
MetaRNN	Uncertain	0.47	T
MetaSVM	Benign	-0.39	T
MutationAssessor	Benign	1.1	L
PhyloP100		9.3
PrimateAI	Uncertain	0.75	T
PROVEAN	Uncertain	-4.2	D
REVEL	Uncertain	0.49
Sift	Uncertain	0.0020	D
Polyphen		0.99	D
Vest4		0.65
MutPred		0.47		Gain of methylation at K27406 (P = 0.0351)
MVP		0.73
MPC		0.49
ClinPred		0.29	T
GERP RS		5.7
Mutation Taster		=31/69	disease causing

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

Other links and lift over

dbSNP: rs143975327; hg19: chr2-179422944;