2-178579070-C-G

Variant names:

• chr2-178579070-C-G
• rs144295295
• NM_001267550.2:c.67960G>C

Variant summary

Our verdict is Benign. The variant received -7 ACMG points: 0P and 7B. BP4_Moderate BP6 BS1

The NM_001267550.2(TTN):​c.67960G>C​(p.Asp22654His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000614 in 1,613,316 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. 15/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. D22654D) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000033 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000064 (1 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:4
• Conservation: PhyloP100: 3.29
• Publications: 1 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]

ENSG00000270574 (HGNC:):

ACMG classification

Our verdict: Benign. The variant received -7 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.07675564).
• BP6: Variant 2-178579070-C-G is Benign according to our data. Variant chr2-178579070-C-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 47258.We mark this variant Likely_benign, oryginal submission is: [Conflicting_classifications_of_pathogenicity].
• BS1: Variant frequency is greater than expected in population eas. GnomAdExome4 allele frequency = 0.0000643 (94/1461136) while in subpopulation EAS AF = 0.00232 (92/39570). AF 95% confidence interval is 0.00194. There are 1 homozygotes in GnomAdExome4. There are 50 alleles in the male GnomAdExome4 subpopulation. Median coverage is 33. This position passed quality control check.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.67960G>C	p.Asp22654His	missense_variant	Exon 320 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.67960G>C	p.Asp22654His	missense_variant	Exon 320 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.0000329 AC: 5 AN: 152062 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000970

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: 0.0000282 AC: 7 AN: 248202 AF XY: 0.0000371

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000290

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000337

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000643 AC: 94 AN: 1461136 Hom.: 1 Cov.: 33 AF XY: 0.0000688 AC XY: 50 AN XY: 726856

African (AFR) AF: 0.00 AC: 0 AN: 33446

American (AMR) AF: 0.0000224 AC: 1 AN: 44700

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26122

East Asian (EAS) AF: 0.00232 AC: 92 AN: 39570

South Asian (SAS) AF: 0.00 AC: 0 AN: 86248

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53382

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111562

Other (OTH) AF: 0.0000166 AC: 1 AN: 60344

GnomAD4 genome AF: 0.0000329 AC: 5 AN: 152180 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74392

African (AFR) AF: 0.00 AC: 0 AN: 41554

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

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

East Asian (EAS) AF: 0.000972 AC: 5 AN: 5142

South Asian (SAS) AF: 0.00 AC: 0 AN: 4820

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 67968

Other (OTH) AF: 0.00 AC: 0 AN: 2114

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ExAC AF: 0.0000414 AC: 5

Asia WGS AF: 0.000577 AC: 2 AN: 3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3 Benign:4

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not specified Uncertain:2

Jun 07, 2016

Athena Diagnostics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jul 31, 2012

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant classified as Uncertain Significance - Favor Benign. The Asp20086His var iant in TTN has not been reported in the literature but has been identified in 1 /194 Chinese and 2/178 Japanese individuals (dbSNP rs144295295, 1000 Genomes Pro ject). This frequency raises the possibility that the variant is not disease cau sing but is too low to rule out an effect. The affected amino acid is not well c onserved in evolution, also arguing against an impact of the variant to the prot ein. Additional information is needed to fully assess its clinical significance. -

Dilated cardiomyopathy 1G Uncertain:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

Autosomal recessive limb-girdle muscular dystrophy type 2J Benign:1

Jun 20, 2017

Illumina Laboratory Services, Illumina

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases allowed determination this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -

Early-onset myopathy with fatal cardiomyopathy Benign:1

Jun 20, 2017

Illumina Laboratory Services, Illumina

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -

Myopathy, myofibrillar, 9, with early respiratory failure Benign:1

Jun 20, 2017

Illumina Laboratory Services, Illumina

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -

Tibial muscular dystrophy Benign:1

Jun 20, 2017

Illumina Laboratory Services, Illumina

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.19
BayesDel_addAF	Benign	-0.29	T
BayesDel_noAF	Benign	-0.35
CADD	Benign	21
DANN	Benign	0.86
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.62
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.88	D;D;D;.;D;D;D
M_CAP	Benign	0.037	D
MetaRNN	Benign	0.077	T;T;T;T;T;T;T
MetaSVM	Benign	-0.64	T
MutationAssessor	Benign	1.8	.;.;.;L;.;.;L
PhyloP100		3.3
PrimateAI	Benign	0.47	T
PROVEAN	Uncertain	-4.2	D;D;.;.;D;D;.
REVEL	Benign	0.27
Sift	Uncertain	0.0070	D;D;.;.;D;D;.
Polyphen		0.93	.;.;.;P;.;.;P
Vest4		0.20
MVP		0.28
MPC		0.31
ClinPred		0.20	T
GERP RS		5.7
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: rs144295295; hg19: chr2-179443797;