2-178550974-A-T

Variant names:

• chr2-178550974-A-T
• rs202185465
• NM_001267550.2:c.91557T>A

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001267550.2(TTN):​c.91557T>A​(p.Asp30519Glu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000263 in 152,138 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/20 in silico tools predict 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. D30519D) has been classified as Likely benign.

• Frequency: Genomes: 𝑓 0.000026 (0 hom., cov: 33)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.78
• 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]

ACMG classification

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.24529314).

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.91557T>A	p.Asp30519Glu	missense	Exon 336 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.86634T>A	p.Asp28878Glu	missense	Exon 286 of 313	NP_001243779.1
	TTN	NM_133378.4		c.83853T>A	p.Asp27951Glu	missense	Exon 285 of 312	NP_596869.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.91557T>A	p.Asp30519Glu	missense	Exon 336 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.91401T>A	p.Asp30467Glu	missense	Exon 334 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.91281T>A	p.Asp30427Glu	missense	Exon 334 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.0000263 AC: 4 AN: 152138 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000965

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: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00000405 AC: 1 AN: 246834 AF XY: 0.00

Gnomad AFR exome AF: 0.0000648

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome Cov.: 31

GnomAD4 genome AF: 0.0000263 AC: 4 AN: 152138 Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2 AN XY: 74320

African (AFR) AF: 0.0000965 AC: 4 AN: 41444

American (AMR) AF: 0.00 AC: 0 AN: 15258

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5184

South Asian (SAS) AF: 0.00 AC: 0 AN: 4826

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10616

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68022

Other (OTH) AF: 0.00 AC: 0 AN: 2092

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ExAC AF: 0.00000828 AC: 1

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.64
BayesDel_addAF	Benign	-0.21	T
BayesDel_noAF	Benign	-0.35
CADD	Benign	8.7
DANN	Benign	0.93
Eigen	Uncertain	0.31
Eigen_PC	Uncertain	0.28
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Benign	0.84	T
M_CAP	Benign	0.026	D
MetaRNN	Benign	0.25	T
MetaSVM	Benign	-0.61	T
MutationAssessor	Benign	1.8	L
PhyloP100		1.8
PrimateAI	Uncertain	0.58	T
PROVEAN	Uncertain	-2.7	D
REVEL	Benign	0.15
Sift	Benign	0.10	T
Polyphen		1.0	D
Vest4		0.46
MutPred		0.27		Gain of disorder (P = 0.1037)
MVP		0.24
MPC		0.45
ClinPred		0.34	T
GERP RS		2.1
Mutation Taster		=73/27	polymorphism

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: rs202185465; hg19: chr2-179415701;