1-229432295-C-A

Position:

• chr1-229432295-C-A

Variant summary

Our verdict is Pathogenic. Variant got 15 ACMG points: 15P and 0B. PM1 PM2 PP2 PP3_Moderate PP5_Very_Strong

The NM_001100.4(ACTA1):​c.591G>T​(p.Glu197Asp) variant causes a missense change. 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 Uncertain significancein ClinVar.

• Frequency: Genomes: not found (cov: 31)
• Consequence: ACTA1 NM_001100.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 4.07

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 15 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_001100.4
• PM2: Very rare variant in population databases, with high coverage
• 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, 0.892
• PP5: Variant 1-229432295-C-A is Pathogenic according to our data. Variant chr1-229432295-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 224412.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-229432295-C-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ACTA1	NM_001100.4	c.591G>T	p.Glu197Asp	missense_variant	4/7	ENST00000366684.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ACTA1	ENST00000366684.7	c.591G>T	p.Glu197Asp	missense_variant	4/7	1	NM_001100.4	P1
ACTA1	ENST00000366683.4	c.591G>T	p.Glu197Asp	missense_variant	4/7	5
ACTA1	ENST00000684723.1	c.456G>T	p.Glu152Asp	missense_variant	3/6

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 31

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

Labcorp Genetics (formerly Invitae), Labcorp

Apr 06, 2022

For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). ClinVar contains an entry for this variant (Variation ID: 224412). This missense change has been observed in individuals with autosomal dominant ACTA1-related disorders (PMID: 25938801, 30732915). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glutamic acid, which is acidic and polar, with aspartic acid, which is acidic and polar, at codon 197 of the ACTA1 protein (p.Glu197Asp). -

Progressive scapulohumeroperoneal distal myopathy Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Jul 16, 2024

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Jun 05, 2023

Previously reported in a parent and child with distal myopathy with nemaline rods on muscle biopsy (Hernandez-Lain et al., 2019); Not observed at significant frequency in large population cohorts (gnomAD); Missense variants in this gene are often considered pathogenic (HGMD); 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: 25470062, 25938801, 30732915, 27519468, 29433794) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.92
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.33
CADD	Uncertain	24
DANN	Benign	0.88
DEOGEN2	Pathogenic	0.92	D
Eigen	Benign	-0.31
Eigen_PC	Benign	-0.22
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.93	D
M_CAP	Pathogenic	0.77	D
MetaRNN	Pathogenic	0.89	D
MetaSVM	Uncertain	0.31	D
MutationAssessor	Benign	1.8	L
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.89	D
PROVEAN	Benign	-2.1	N
REVEL	Uncertain	0.60
Sift4G	Benign	0.085	T
Polyphen		0.0	B
Vest4		0.91
MutPred		0.66		Gain of ubiquitination at K193 (P = 0.1106);
MVP		0.96
ClinPred		0.88	D
GERP RS		3.5
Varity_R		0.88
gMVP		0.94

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs869312739; hg19: chr1-229568042;