2-178775043-T-A

Variant names:

• chr2-178775043-T-A
• rs372979075
• NM_001267550.2:c.6668A>T

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 0P and 5B. BP4_Strong BP6

The NM_001267550.2(TTN):​c.6668A>T​(p.His2223Leu) variant causes a missense change. The variant allele was found at a frequency of 0.0000235 in 1,614,026 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 0.000053 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000021 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:4
• Conservation: PhyloP100: 6.27
• 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 -5 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.056794345).
• BP6: Variant 2-178775043-T-A is Benign according to our data. Variant chr2-178775043-T-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 192075.

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

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.6668A>T	p.His2223Leu	missense	Exon 29 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.6668A>T	p.His2223Leu	missense	Exon 29 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.6668A>T	p.His2223Leu	missense	Exon 29 of 312	NP_596869.4	Q8WZ42-11

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.6668A>T	p.His2223Leu	missense	Exon 29 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.6668A>T	p.His2223Leu	missense	Exon 29 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.6392A>T	p.His2131Leu	missense	Exon 27 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.0000526 AC: 8 AN: 152178 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00116

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.000478

GnomAD2 exomes AF: 0.0000677 AC: 17 AN: 251140 AF XY: 0.0000884

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000600

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000205 AC: 30 AN: 1461730 Hom.: 0 Cov.: 33 AF XY: 0.0000330 AC XY: 24 AN XY: 727166

African (AFR) AF: 0.00 AC: 0 AN: 33470

American (AMR) AF: 0.0000224 AC: 1 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

East Asian (EAS) AF: 0.000353 AC: 14 AN: 39654

South Asian (SAS) AF: 0.000151 AC: 13 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53398

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111942

Other (OTH) AF: 0.0000331 AC: 2 AN: 60392

GnomAD4 genome AF: 0.0000525 AC: 8 AN: 152296 Hom.: 0 Cov.: 33 AF XY: 0.0000403 AC XY: 3 AN XY: 74468

African (AFR) AF: 0.00 AC: 0 AN: 41564

American (AMR) AF: 0.00 AC: 0 AN: 15292

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

East Asian (EAS) AF: 0.00116 AC: 6 AN: 5182

South Asian (SAS) AF: 0.000207 AC: 1 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: 68026

Other (OTH) AF: 0.000473 AC: 1 AN: 2114

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000189

ExAC AF: 0.0000824 AC: 10

Asia WGS AF: 0.00520 AC: 18 AN: 3478

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	4	1	not provided (5)
-	1	-	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 (1)
-	1	-	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)
-	-	1	Cardiomyopathy (1)
-	1	-	Cardiovascular phenotype (1)
-	-	1	Hypertrophic cardiomyopathy (1)
-	-	1	not specified (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.34
BayesDel_addAF	Benign	-0.22	T
BayesDel_noAF	Benign	-0.20
CADD	Benign	21
DANN	Benign	0.88
Eigen	Benign	-0.16
Eigen_PC	Benign	0.037
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Benign	0.80	T
M_CAP	Uncertain	0.12	D
MetaRNN	Benign	0.057	T
MetaSVM	Benign	-0.79	T
PhyloP100		6.3
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-7.3	D
REVEL	Uncertain	0.37
Sift	Benign	0.32	T
Sift4G	Uncertain	0.0020	D
Polyphen		0.0080	B
Vest4		0.51
MutPred		0.44		Loss of disorder (P = 0.0396)
MVP		0.51
MPC		0.11
ClinPred		0.15	T
GERP RS		4.3
Mutation Taster		=57/43	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs372979075; hg19: chr2-179639770; COSMIC: COSV104644727; COSMIC: COSV104644727;