1-229433036-T-C

Position:

• chr1-229433036-T-C

Variant summary

Our verdict is Pathogenic. Variant got 13 ACMG points: 13P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Moderate

The NM_001100.4(ACTA1):​c.80A>G​(p.Asp27Gly) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D27N) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: ACTA1 NM_001100.4 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 8.00

Genes affected

ACTA1 (HGNC:129): (actin alpha 1, skeletal muscle) The product encoded by this gene belongs to the actin family of proteins, which are highly conserved proteins that play a role in cell motility, structure and integrity. Alpha, beta and gamma actin isoforms have been identified, with alpha actins being a major constituent of the contractile apparatus, while beta and gamma actins are involved in the regulation of cell motility. This actin is an alpha actin that is found in skeletal muscle. Mutations in this gene cause a variety of myopathies, including nemaline myopathy, congenital myopathy with excess of thin myofilaments, congenital myopathy with cores, and congenital myopathy with fiber-type disproportion, diseases that lead to muscle fiber defects with manifestations such as hypotonia. [provided by RefSeq, Sep 2019]

ACMG classification

Verdict is Pathogenic. Variant got 13 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, 8 uncertain in NM_001100.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-229433037-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 3068434.Status of the report is no_assertion_criteria_provided, 0 stars.
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), ACTA1. . Gene score misZ 4.5292 (greater than the threshold 3.09). Trascript score misZ 6.088 (greater than threshold 3.09). GenCC has associacion of gene with congenital myopathy with excess of thin filaments, nemaline myopathy 3, intermediate nemaline myopathy, typical nemaline myopathy, congenital fiber-type disproportion myopathy, severe congenital nemaline myopathy, rigid spine syndrome, zebra body myopathy, childhood-onset nemaline myopathy, congenital myopathy 2c, severe infantile, autosomal dominant, alpha-actinopathy, progressive scapulohumeroperoneal distal myopathy.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.984
• PP5: Variant 1-229433036-T-C is Pathogenic according to our data. Variant chr1-229433036-T-C is described in ClinVar as [Pathogenic]. Clinvar id is 464133.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ACTA1	NM_001100.4	c.80A>G	p.Asp27Gly	missense_variant	2/7	ENST00000366684.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ACTA1	ENST00000366684.7	c.80A>G	p.Asp27Gly	missense_variant	2/7	1	NM_001100.4	P1
ACTA1	ENST00000366683.4	c.80A>G	p.Asp27Gly	missense_variant	2/7	5
ACTA1	ENST00000684723.1	c.-6-156A>G		intron_variant

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 38

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Actin accumulation myopathy Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Jan 02, 2024

This sequence change replaces aspartic acid, which is acidic and polar, with glycine, which is neutral and non-polar, at codon 27 of the ACTA1 protein (p.Asp27Gly). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with clinical features of autosomal dominant congenital myopathy (Invitae). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 464133). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on ACTA1 protein function. This variant disrupts the p.Asp27 amino acid residue in ACTA1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 12921789, 19562689). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.27
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.92	D;D
Eigen	Pathogenic	0.81
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.94	D;D
M_CAP	Pathogenic	0.42	D
MetaRNN	Pathogenic	0.98	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.7	H;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.85	D
PROVEAN	Uncertain	-3.2	D;N
REVEL	Pathogenic	0.88
Sift	Uncertain	0.0020	.;D
Sift4G	Uncertain	0.0090	D;D
Polyphen		0.97	D;.
Vest4		0.92
MutPred		0.93		Gain of methylation at R30 (P = 0.1218);Gain of methylation at R30 (P = 0.1218);
MVP		0.98
ClinPred		0.99	D
GERP RS		4.7
Varity_R		0.99
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1553255534; hg19: chr1-229568783;