1-229433007-C-G

Variant summary

Our verdict is Pathogenic. Variant got 27 ACMG points: 27P and 0B. PS1_Very_Strong PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_001100.4(ACTA1):c.109G>C(p.Val37Leu) 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 nucleotide change resulting in same amino acid change has been previously reported as Pathogenicin ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V37A) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: ACTA1 NM_001100.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 7.88

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 27 ACMG points.

• PS1: Transcript NM_001100.4 (ACTA1) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar as 464114
• PM1: In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 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 chr1-229433006-A-G is described in Lovd as [Pathogenic].
• PP2: Missense variant where missense usually causes diseases, ACTA1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.981
• PP5: Variant 1-229433007-C-G is Pathogenic according to our data. Variant chr1-229433007-C-G is described in ClinVar as [Pathogenic]. Clinvar id is 639455.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-229433007-C-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ACTA1	NM_001100.4	c.109G>C	p.Val37Leu	missense_variant	2/7	ENST00000366684.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ACTA1	ENST00000366684.7	c.109G>C	p.Val37Leu	missense_variant	2/7	1	NM_001100.4	P1
ACTA1	ENST00000366683.4	c.109G>C	p.Val37Leu	missense_variant	2/7	5
ACTA1	ENST00000684723.1	c.-6-127G>C		intron_variant

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 38

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Actin accumulation myopathy Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Jul 17, 2023

This sequence change replaces valine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 37 of the ACTA1 protein (p.Val37Leu). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with autosomal dominant nemaline myopathy (PMID: 12921789, 15236405, 19562689). In at least one individual the variant was observed to be de novo. This variant is also known as c.212G_x0007_>C. ClinVar contains an entry for this variant (Variation ID: 639455). 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 ACTA1 protein function. For these reasons, this variant has been classified as Pathogenic. -

See cases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Center for Personalized Medicine, Children's Hospital Los Angeles

Dec 21, 2022

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

CeGaT Center for Human Genetics Tuebingen

Sep 01, 2018

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.97
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.51
Cadd	Pathogenic	27
Dann	Uncertain	0.98
DEOGEN2	Pathogenic	0.87	D;T
Eigen	Pathogenic	0.72
Eigen_PC	Pathogenic	0.67
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D
M_CAP	Pathogenic	0.55	D
MetaRNN	Pathogenic	0.98	D;D
MetaSVM	Pathogenic	1.2	D
MutationAssessor	Pathogenic	3.1	M;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.91	D
PROVEAN	Benign	-1.4	N;N
REVEL	Pathogenic	0.88
Sift4G	Uncertain	0.047	D;D
Polyphen		0.62	P;.
Vest4		0.85
MutPred		0.92		Loss of loop (P = 0.1242);Loss of loop (P = 0.1242);
MVP		0.97
ClinPred		0.97	D
GERP RS		4.5
Varity_R		0.90
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs1553255521; hg19: chr1-229568754;