1-229433034-C-G

Position:

• chr1-229433034-C-G

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP2 PP3_Strong

The NM_001100.4(ACTA1):​c.82G>C​(p.Ala28Pro) 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A28C) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: ACTA1 NM_001100.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.89

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 11 ACMG points.

• PM1: In a hotspot region, there are 4 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 chr1-229433033-G-T is described in Lovd as [Likely_pathogenic].
• 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, 0.966

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ACTA1	NM_001100.4	c.82G>C	p.Ala28Pro	missense_variant	2/7	ENST00000366684.7	NP_001091.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ACTA1	ENST00000366684.7	c.82G>C	p.Ala28Pro	missense_variant	2/7	1	NM_001100.4	ENSP00000355645.3
ACTA1	ENST00000366683.4	c.82G>C	p.Ala28Pro	missense_variant	2/7	5		ENSP00000355644.4
ACTA1	ENST00000684723.1	c.-6-154G>C		intron_variant				ENSP00000508084.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 38

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Actin accumulation myopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Baylor Genetics

Sep 01, 2017

At time of reporting, this mutation was novel. Likely pathogenicity based on de novo finding in a 1-month-old male with arthrogryposis, club feet, hypotonia, absent reflexes, respiratory insufficiency, myopathy -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.37
CADD	Pathogenic	30
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.90	D;T
Eigen	Pathogenic	0.72
Eigen_PC	Uncertain	0.62
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.94	D;D
M_CAP	Pathogenic	0.52	D
MetaRNN	Pathogenic	0.97	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.7	H;.
PrimateAI	Pathogenic	0.90	D
PROVEAN	Uncertain	-2.4	N;N
REVEL	Pathogenic	0.86
Sift	Pathogenic	0.0	.;D
Sift4G	Uncertain	0.014	D;D
Polyphen		0.66	P;.
Vest4		0.87
MutPred		0.86		Gain of disorder (P = 0.0483);Gain of disorder (P = 0.0483);
MVP		0.98
ClinPred		1.0	D
GERP RS		4.7
Varity_R		0.99
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.050		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: rs546670743; hg19: chr1-229568781;