1-229431506-C-G

Variant names:

• chr1-229431506-C-G
• NM_001100.4:c.1127G>C

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PS2 PP4_Moderate PP2 PP3 PM2_Supporting PS4_Supporting

This summary comes from the ClinGen Evidence Repository: The variant NM_001100.4:c.1127G>C in ACTA1 is a missense variant predicted to cause substitution of cysteine by serine at amino acid 376 (p.Cys376Ser) in exon 7/7. The variant is absent from gnomAD v2.1.1 with adequate coverage (PM2_Supporting). The REVEL computational prediction analysis tool gives a score of 0.946, which is above the threshold necessary to apply PP3. In addition, ACTA1, in which the variant was identified, is defined by the ClinGen Congenital Myopathies VCEP as a gene that has a low rate of benign missense variation and where pathogenic missense variants are a common mechanism of disease (PP2). The Z-score in gnomAD v2.1.1 is 4.53 which is above the threshold necessary to apply PP2. This variant has been reported in two probands with congenital nemaline myopathy (PS4_Supporting, PP4_Moderate PMID:25890230,19562689), and as a de novo observation with confirmed parental relationships in one of the probands (PS2, PMID:25890230). In summary, the variant meets the criteria to be classified as Pathogenic for autosomal dominant alpha-actinopathy. ACMG/AMP criteria met, as specified by the ClinGen Congenital Myopathies VCEP: PS2, PP4_Moderate, PS4_Supporting, PP2, PP3, PM2_Supporting (ClinGen Congenital Myopathies VCEP specifications version 2; 08/27/2024). LINK:https://erepo.genome.network/evrepo/ui/classification/CA345144077/MONDO:0100084/147

• Frequency: Genomes: not found (cov: 32)
• Consequence: ACTA1 NM_001100.4 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:1
• Conservation: PhyloP100: 7.86
• Publications: 1 publications found

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]

ACTA1 Gene-Disease associations (from GenCC):

• alpha-actinopathy

  Inheritance: AR, AD Classification: DEFINITIVE Submitted by: ClinGen
• congenital myopathy 2a, typical, autosomal dominant

  Inheritance: AR, SD, AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics
• congenital myopathy with excess of thin filaments

  Inheritance: SD Classification: DEFINITIVE Submitted by: Illumina
• congenital myopathy 2c, severe infantile, autosomal dominant

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• childhood-onset nemaline myopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• congenital fiber-type disproportion myopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• intermediate nemaline myopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• progressive scapulohumeroperoneal distal myopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• typical nemaline myopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• rigid spine syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• severe congenital nemaline myopathy

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• zebra body myopathy

  Inheritance: Unknown Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000290037 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PS2: For more information check the summary or visit ClinGen Evidence Repository.
• PS4: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.
• PP2: For more information check the summary or visit ClinGen Evidence Repository.
• PP3: For more information check the summary or visit ClinGen Evidence Repository.
• PP4: For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ACTA1	NM_001100.4	c.1127G>C	p.Cys376Ser	missense_variant	Exon 7 of 7	ENST00000366684.7	NP_001091.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ACTA1	ENST00000366684.7	c.1127G>C	p.Cys376Ser	missense_variant	Exon 7 of 7	1	NM_001100.4	ENSP00000355645.3
ACTA1	ENST00000366683.4	c.1049G>C	p.Cys350Ser	missense_variant	Exon 7 of 7	5		ENSP00000355644.4
ACTA1	ENST00000684723.1	c.992G>C	p.Cys331Ser	missense_variant	Exon 6 of 6			ENSP00000508084.1
ENSG00000290037	ENST00000702606.2	n.141C>G		non_coding_transcript_exon_variant	Exon 1 of 1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: reviewed by expert panel

Submissions by phenotype

Alpha-actinopathy Pathogenic:1

Aug 27, 2024

ClinGen Congenital Myopathies Variant Curation Expert Panel, ClinGen

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

The variant NM_001100.4:c.1127G>C in ACTA1 is a missense variant predicted to cause substitution of cysteine by serine at amino acid 376 (p.Cys376Ser) in exon 7/7. The variant is absent from gnomAD v2.1.1 with adequate coverage (PM2_Supporting). The REVEL computational prediction analysis tool gives a score of 0.946, which is above the threshold necessary to apply PP3. In addition, ACTA1, in which the variant was identified, is defined by the ClinGen Congenital Myopathies VCEP as a gene that has a low rate of benign missense variation and where pathogenic missense variants are a common mechanism of disease (PP2). The Z-score in gnomAD v2.1.1 is 4.53 which is above the threshold necessary to apply PP2. This variant has been reported in two probands with congenital nemaline myopathy (PS4_Supporting, PP4_Moderate PMID:25890230,19562689), and as a de novo observation with confirmed parental relationships in one of the probands (PS2, PMID:25890230). In summary, the variant meets the criteria to be classified as Pathogenic for autosomal dominant alpha-actinopathy. ACMG/AMP criteria met, as specified by the ClinGen Congenital Myopathies VCEP: PS2, PP4_Moderate, PS4_Supporting, PP2, PP3, PM2_Supporting (ClinGen Congenital Myopathies VCEP specifications version 2; 08/27/2024). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.54
CADD	Pathogenic	28
DANN	Benign	0.96
DEOGEN2	Pathogenic	0.97	D;D
Eigen	Pathogenic	0.78
Eigen_PC	Pathogenic	0.67
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Pathogenic	1.0	D;D
M_CAP	Pathogenic	0.60	D
MetaRNN	Pathogenic	0.94	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.2	M;.
PhyloP100		7.9
PrimateAI	Pathogenic	0.88	D
PROVEAN	Uncertain	-3.8	D;.
REVEL	Pathogenic	0.95
Sift4G	Uncertain	0.010	D;D
Polyphen		0.94	P;.
Vest4		0.94
MutPred		0.77		Gain of disorder (P = 0.0026);.;
MVP		0.99
ClinPred		1.0	D
GERP RS		3.9
Varity_R		0.95
gMVP		0.99
Mutation Taster		=0/100	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

hg19: chr1-229567253;