rs79666048

Variant names:

• chr2-178532600-G-A
• rs79666048
• NM_001267550.2:c.104015C>T

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 0P and 3B. BP4_Moderate BP6

The NM_001267550.2(TTN):​c.104015C>T​(p.Ala34672Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000322 in 1,613,886 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000034 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:1
• Conservation: PhyloP100: 7.73
• Publications: 2 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: Likely_benign. The variant received -3 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.16641513).
• BP6: Variant 2-178532600-G-A is Benign according to our data. Variant chr2-178532600-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 238694.

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.104015C>T	p.Ala34672Val	missense	Exon 358 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.99092C>T	p.Ala33031Val	missense	Exon 308 of 313	NP_001243779.1
	TTN	NM_133378.4		c.96311C>T	p.Ala32104Val	missense	Exon 307 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.104015C>T	p.Ala34672Val	missense	Exon 358 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.103859C>T	p.Ala34620Val	missense	Exon 356 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.103739C>T	p.Ala34580Val	missense	Exon 356 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152090 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: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000441

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000201 AC: 5 AN: 249004 AF XY: 0.00000740

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: 0.0000443

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000335 AC: 49 AN: 1461678 Hom.: 0 Cov.: 40 AF XY: 0.0000289 AC XY: 21 AN XY: 727122

African (AFR) AF: 0.00 AC: 0 AN: 33474

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53402

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.0000423 AC: 47 AN: 1111844

Other (OTH) AF: 0.0000331 AC: 2 AN: 60374

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152208 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74402

African (AFR) AF: 0.00 AC: 0 AN: 41526

American (AMR) AF: 0.00 AC: 0 AN: 15290

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5166

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

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10600

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

European-Non Finnish (NFE) AF: 0.0000441 AC: 3 AN: 68014

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

Alfa AF: 0.0000354 Hom.: 0

Bravo AF: 0.0000151

TwinsUK AF: 0.000270 AC: 1

ALSPAC AF: 0.00 AC: 0

ExAC AF: 0.00000827 AC: 1

EpiCase AF: 0.000164

EpiControl AF: 0.00

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	2	1	not provided (3)
-	1	-	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.40
BayesDel_addAF	Benign	-0.15	T
BayesDel_noAF	Benign	-0.32
CADD	Benign	21
DANN	Benign	0.97
Eigen	Uncertain	0.38
Eigen_PC	Uncertain	0.55
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.93	D
M_CAP	Benign	0.034	D
MetaRNN	Benign	0.17	T
MetaSVM	Benign	-0.81	T
MutationAssessor	Benign	0.0	N
PhyloP100		7.7
PrimateAI	Uncertain	0.67	T
PROVEAN	Uncertain	-2.7	D
REVEL	Benign	0.27
Sift	Uncertain	0.0040	D
Polyphen		0.84	P
Vest4		0.26
MVP		0.50
MPC		0.13
ClinPred		0.33	T
GERP RS		6.1
Mutation Taster		=89/11	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: rs79666048; hg19: chr2-179397327;