10-88939548-C-T

Variant names:

• chr10-88939548-C-T
• rs766734961
• NM_001613.4:c.767G>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5

The NM_001613.4(ACTA2):​c.767G>A​(p.Arg256His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,700 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 13/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R256C) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: ACTA2 NM_001613.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1
• Conservation: PhyloP100: 7.91
• Publications: 8 publications found

Genes affected

ACTA2 (HGNC:130): (actin alpha 2, smooth muscle) This gene encodes one of six different actin proteins. Actins are highly conserved proteins that are involved in cell motility, structure, integrity, and intercellular signaling. The encoded protein is a smooth muscle actin that is involved in vascular contractility and blood pressure homeostasis. Mutations in this gene cause a variety of vascular diseases, such as thoracic aortic disease, coronary artery disease, stroke, and Moyamoya disease, as well as multisystemic smooth muscle dysfunction syndrome. [provided by RefSeq, Sep 2017]

ACTA2-AS1 (HGNC:45169): (ACTA2 antisense RNA 1)

STAMBPL1 (HGNC:24105): (STAM binding protein like 1) Predicted to enable Lys63-specific deubiquitinase activity and thiol-dependent deubiquitinase. Predicted to be involved in protein K63-linked deubiquitination. Located in membrane. [provided by Alliance of Genome Resources, Apr 2022]

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 10 uncertain in NM_001613.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr10-88939549-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 263578.
• PP2: Missense variant in the ACTA2 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 27 curated pathogenic missense variants (we use a threshold of 10). The gene has 0 curated benign missense variants. Trascript score misZ: 4.6117 (above the threshold of 3.09). GenCC associations: The gene is linked to multisystemic smooth muscle dysfunction syndrome, connective tissue disorder, familial thoracic aortic aneurysm and aortic dissection, Moyamoya disease 5, aortic aneurysm, familial thoracic 6.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.981
• PP5: Variant 10-88939548-C-T is Pathogenic according to our data. Variant chr10-88939548-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 264363.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ACTA2	NM_001613.4	c.767G>A	p.Arg256His	missense_variant	Exon 7 of 9	ENST00000224784.10	NP_001604.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ACTA2	ENST00000224784.10	c.767G>A	p.Arg256His	missense_variant	Exon 7 of 9	1	NM_001613.4	ENSP00000224784.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461700 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727148

African (AFR) AF: 0.00 AC: 0 AN: 33476

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

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39686

South Asian (SAS) AF: 0.00 AC: 0 AN: 86242

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5690

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1111956

Other (OTH) AF: 0.00 AC: 0 AN: 60380

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Familial thoracic aortic aneurysm and aortic dissection Pathogenic:1

Aug 06, 2024

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.R256H variant (also known as c.767G>A), located in coding exon 6 of the ACTA2 gene, results from a G to A substitution at nucleotide position 767. The arginine at codon 256 is replaced by histidine, an amino acid with highly similar properties. Based on internal structural analysis, this alteration is deleterious, being highly destabilizing to the local structure (Ambry internal data). Additionally, this alteration has been reported in individuals with thoracic aortic aneurysm and dissection (TAAD) (Weerakkody R et al. Genet Med, 2018 Nov;20:1414-1422; Ambry internal data; external communication). This missense alteration is located in a region that has a low rate of benign missense variation (Lek M et al. Nature. 2016 Aug 18;536(7616):285-91; DECIPHER: Database of Chromosomal Imbalance and Phenotype in Humans using Ensembl Resources. Firth H.V. et al. 2009. Am.J.Hum.Genet. 84, 524-533 (DOI: dx.doi.org/10/1016/j.ajhg.2009.03.010)). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Aortic aneurysm, familial thoracic 6 Pathogenic:1

Feb 14, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Arg256 amino acid residue in ACTA2. Other variant(s) that disrupt this residue have been observed in individuals with ACTA2-related conditions (Invitae), which suggests that this may be a clinically significant amino acid residue. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt ACTA2 protein function. ClinVar contains an entry for this variant (Variation ID: 264363). This missense change has been observed in individuals with clinical features of thoracic aortic aneurysms and dissections (PMID: 29543232; Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with histidine, which is basic and polar, at codon 256 of the ACTA2 protein (p.Arg256His). -

not provided Uncertain:1

Nov 04, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 29543232) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	32
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.93	D
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.96	D
M_CAP	Pathogenic	0.64	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.3	H
PhyloP100		7.9
PrimateAI	Pathogenic	0.92	D
PROVEAN	Uncertain	-4.1	D
REVEL	Pathogenic	0.94
Sift4G	Uncertain	0.018	D
Polyphen		1.0	D
Vest4		0.91
MutPred		0.87		Loss of methylation at R256 (P = 0.1106);
MVP		0.98
ClinPred		1.0	D
GERP RS		6.1
Varity_R		0.88
gMVP		0.96
Mutation Taster		=32/68	disease causing

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: rs766734961; hg19: chr10-90699305; COSMIC: COSV56518179; COSMIC: COSV56518179;