Genetic Variant TTN:p.Leu16469His (chr2-178613877-A-T) – ACMG Classification: Benign (-8 pts)

Variant summary

Our verdict is Benign. The variant received -8 ACMG points: 1P and 9B. PP3BP4_StrongBP6BS1

The NM_001267550.2(TTN):c.49406T>A(p.Leu16469His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000645 in 1,611,210 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.000059 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000065 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2B:5

Conservation

PhyloP100: 9.27

Publications

1 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:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -8 ACMG points.

PP3

Multiple lines of computational evidence support a deleterious effect 8: AlphaMissense, Eigen, MutationAssessor, phyloP100way_vertebrate, PrimateAI, PROVEAN, REVEL, REVEL [when BayesDel_addAF, Dann, max_spliceai, FATHMM_MKL, MetaRNN, MutationTaster was below the threshold]

BP4

Computational evidence support a benign effect (MetaRNN=0.06670746).

BP6

Variant 2-178613877-A-T is Benign according to our data. Variant chr2-178613877-A-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 413216.

BS1

Variant frequency is greater than expected in population amr. GnomAdExome4 allele frequency = 0.0000651 (95/1459242) while in subpopulation AMR AF = 0.00212 (94/44440). AF 95% confidence interval is 0.00177. There are 0 homozygotes in GnomAdExome4. There are 41 alleles in the male GnomAdExome4 subpopulation. Median coverage is 32. This position passed quality control check.

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	HGVSp	Effect	Exon Rank	Protein
TTN	NM_001267550.2	MANE Select	c.49406T>A	p.Leu16469His	missense	Exon 263 of 363	NP_001254479.2
TTN	NM_001256850.1		c.44483T>A	p.Leu14828His	missense	Exon 213 of 313	NP_001243779.1
TTN	NM_133378.4		c.41702T>A	p.Leu13901His	missense	Exon 212 of 312	NP_596869.4

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
TTN	ENST00000589042.5	TSL:5 MANE Select	c.49406T>A	p.Leu16469His	missense	Exon 263 of 363	ENSP00000467141.1
TTN	ENST00000446966.2	TSL:1	c.49250T>A	p.Leu16417His	missense	Exon 261 of 361	ENSP00000408004.2
TTN	ENST00000436599.2	TSL:1	c.49130T>A	p.Leu16377His	missense	Exon 261 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes

AF:

0.0000592

AC:

AN:

151968

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000590

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:

0.000345

AC:

AN:

246398

AF XY:

0.000277

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00249

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

AF:

0.0000651

AC:

AN:

1459242

Hom.:

Cov.:

AF XY:

0.0000565

AC XY:

AN XY:

725764

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33336

American (AMR)

AF:

0.00212

AC:

AN:

44440

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26014

East Asian (EAS)

AF:

0.00

AC:

AN:

39620

South Asian (SAS)

AF:

0.00

AC:

AN:

85798

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53314

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5748

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1110704

Other (OTH)

AF:

0.0000166

AC:

AN:

60268

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.482

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:

0.0000592

AC:

AN:

151968

Hom.:

Cov.:

AF XY:

0.0000809

AC XY:

AN XY:

74198

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41422

American (AMR)

AF:

0.000590

AC:

AN:

15246

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5122

South Asian (SAS)

AF:

0.00

AC:

AN:

4824

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10620

Middle Eastern (MID)

AF:

0.00

AC:

AN:

314

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67950

Other (OTH)

AF:

0.00

AC:

AN:

2090

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

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:

0.000106

ExAC

AF:

0.000356

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2Benign:5

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:2Benign:1

Apr 10, 2019

GeneDx

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant is associated with the following publications: (PMID: 26567375)

Jul 02, 2024

Revvity Omics, Revvity

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

May 11, 2017

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

not specified

Benign:2

Sep 21, 2021

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: TTN c.41702T>A (p.Leu13901His) results in a non-conservative amino acid change located in the A-Band of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00034 in 246398 control chromosomes, predominantly at a frequency of 0.0025 within the Latino subpopulation in the gnomAD database. The observed variant frequency within Latino control individuals in the gnomAD database is approximately 4 fold of the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Cardiomyopathy phenotype (0.00063), strongly suggesting that the variant is a benign polymorphism found primarily in populations of Latino origin. The variant was reported in a patient with DCM, without strong evidence for causality (Begay_2015). To our knowledge, no experimental evidence demonstrating its impact on protein function have been reported. Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. Three submitters classified as likely benign/benign while one classified as VUS. Based on the evidence outlined above, the variant was classified as likely benign.

Jul 30, 2024

Athena Diagnostics

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

TTN-related disorder

Benign:1

Mar 18, 2022

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;C1858763:Dilated cardiomyopathy 1G

Benign:1

Dec 17, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

1.0

BayesDel_addAF

Benign

-0.13

BayesDel_noAF

Uncertain

0.030

CADD

Uncertain

(source)

DANN

Benign

0.90

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

1.0

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.89

M_CAP

Uncertain

0.25

MetaRNN

Benign

0.067

MetaSVM

Uncertain

0.59

MutationAssessor

Pathogenic

3.9

PhyloP100

9.3

PrimateAI

Pathogenic

0.82

PROVEAN

Pathogenic

-5.1

REVEL

Pathogenic

0.67

Sift

Uncertain

0.0010

Polyphen

1.0

Vest4

0.61

MVP

0.88

MPC

0.52

ClinPred

0.25

GERP RS

6.1

Mutation Taster

=60/40

polymorphism

(source)

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

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