Genetic Variant TTN:c.34708+8C>A (chr2-178674306-G-T) – ACMG Classification: Benign (-20 pts)

Variant summary

Our verdict is Benign. The variant received -20 ACMG points: 0P and 20B. BP4_StrongBP6_Very_StrongBS1BS2

The NM_001267550.2(TTN):c.34708+8C>A variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000225 in 1,531,886 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Likely benign (★★).

Frequency

Genomes: 𝑓 0.00011 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00024 ( 2 hom. )

Consequence

TTN
NM_001267550.2 splice_region, intron

Scores

Splicing: ADA: 0.00005147

Clinical Significance

Benign/Likely benign criteria provided, multiple submitters, no conflicts B:11

Conservation

PhyloP100: -1.93

Publications

0 publications found

Variant links:

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 links:

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]

TTN-AS1 links:

LOC124906100 (HGNC:):

LOC124906100 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -20 ACMG points.

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.88).

BP6

Variant 2-178674306-G-T is Benign according to our data. Variant chr2-178674306-G-T is described in ClinVar as Benign/Likely_benign. ClinVar VariationId is 238749.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

BS1

Variant frequency is greater than expected in population sas. GnomAdExome4 allele frequency = 0.000238 (328/1380170) while in subpopulation SAS AF = 0.0038 (305/80176). AF 95% confidence interval is 0.00345. There are 2 homozygotes in GnomAdExome4. There are 232 alleles in the male GnomAdExome4 subpopulation. Median coverage is 24. This position passed quality control check.

BS2

High Homozygotes in GnomAdExome4 at 2 AD,AR gene

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

Gene	Transcript	Tags	HGVSc	Effect	Exon Rank	Protein
TTN	NM_001267550.2	MANE Select	c.34708+8C>A	splice_region intron	N/A	NP_001254479.2
TTN	NM_001256850.1		c.33586+8C>A	splice_region intron	N/A	NP_001243779.1
TTN	NM_133378.4		c.30805+8C>A	splice_region intron	N/A	NP_596869.4

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	Effect	Exon Rank	Protein
TTN	ENST00000589042.5	TSL:5 MANE Select	c.34708+8C>A	splice_region intron	N/A	ENSP00000467141.1
TTN	ENST00000446966.2	TSL:1	c.34708+8C>A	splice_region intron	N/A	ENSP00000408004.2
TTN	ENST00000436599.2	TSL:1	c.34432+8C>A	splice_region intron	N/A	ENSP00000405517.2

Frequencies

GnomAD3 genomes

AF:

0.000112

AC:

AN:

151598

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000242

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000264

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00250

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.000464

AC:

AN:

204896

AF XY:

0.000566

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000331

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:

0.000193

GnomAD4 exome

AF:

0.000238

AC:

328

AN:

1380170

Hom.:

Cov.:

AF XY:

0.000338

AC XY:

232

AN XY:

686606

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

31684

American (AMR)

AF:

0.0000245

AC:

AN:

40818

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25180

East Asian (EAS)

AF:

0.00

AC:

AN:

38200

South Asian (SAS)

AF:

0.00380

AC:

305

AN:

80176

European-Finnish (FIN)

AF:

0.00

AC:

AN:

51598

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5636

European-Non Finnish (NFE)

AF:

9.53e-7

AC:

AN:

1049428

Other (OTH)

AF:

0.000366

AC:

AN:

57450

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.447

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.000112

AC:

AN:

151716

Hom.:

Cov.:

AF XY:

0.000148

AC XY:

AN XY:

74162

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41454

American (AMR)

AF:

0.000264

AC:

AN:

15170

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5178

South Asian (SAS)

AF:

0.00250

AC:

AN:

4798

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10562

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67774

Other (OTH)

AF:

0.00

AC:

AN:

2108

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.499

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.0000491

Asia WGS

AF:

0.00231

AC:

AN:

3476

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:11

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not specified

Benign:3

Jun 19, 2017

GeneDx

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease.

Sep 30, 2016

Eurofins Ntd Llc (ga)

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Mar 19, 2020

Al Jalila Children’s Genomics Center, Al Jalila Childrens Speciality Hospital

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

TTN-related disorder

Benign:1

Apr 08, 2019

PreventionGenetics, part of Exact Sciences

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications).

Autosomal recessive limb-girdle muscular dystrophy type 2J

Benign:1

Sep 10, 2021

Genome-Nilou Lab

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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

Benign:1

Jan 01, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Early-onset myopathy with fatal cardiomyopathy

Benign:1

Sep 10, 2021

Genome-Nilou Lab

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1838244:Tibial muscular dystrophy;C1858763:Dilated cardiomyopathy 1G;C1861065:Hypertrophic cardiomyopathy 9;C1863599:Myopathy, myofibrillar, 9, with early respiratory failure;C2673677:Early-onset myopathy with fatal cardiomyopathy

Benign:1

Nov 09, 2021

Fulgent Genetics, Fulgent Genetics

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

See cases

Benign:1

Feb 22, 2019

Centre for Mendelian Genomics, University Medical Centre Ljubljana

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was classified as: Likely benign. The following ACMG criteria were applied in classifying this variant: BP4,BP6.

Myopathy, myofibrillar, 9, with early respiratory failure

Benign:1

Sep 10, 2021

Genome-Nilou Lab

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Tibial muscular dystrophy

Benign:1

Sep 10, 2021

Genome-Nilou Lab

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.88

CADD

Benign

0.029

(source)

DANN

Benign

0.36

PhyloP100

-1.9

Mutation Taster

=100/0

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Benign

0.000051

dbscSNV1_RF

Benign

0.0

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over