NM_001100.4:c.84_85insT

Variant names:

• chr1-229433031-G-GA
• rs753923758
• NM_001100.4:c.84_85insT

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_001100.4(ACTA1):​c.84_85insT​(p.Pro29SerfsTer2) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,544 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: ACTA1 NM_001100.4 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 0.747
• Publications: 0 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

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 211 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-229433031-G-GA is Pathogenic according to our data. Variant chr1-229433031-G-GA is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 464132.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001100.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ACTA1	NM_001100.4	MANE Select	c.84_85insT	p.Pro29SerfsTer2	frameshift	Exon 2 of 7	NP_001091.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ACTA1	ENST00000366684.7	TSL:1 MANE Select	c.84_85insT	p.Pro29SerfsTer2	frameshift	Exon 2 of 7	ENSP00000355645.3
	ACTA1	ENST00000366683.4	TSL:5	c.84_85insT	p.Pro29SerfsTer2	frameshift	Exon 2 of 7	ENSP00000355644.4
	ACTA1	ENST00000684723.1		c.-6-152_-6-151insT		intron	N/A	ENSP00000508084.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.0000160 AC: 4 AN: 250244 AF XY: 0.00000738

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000116

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461544 Hom.: 0 Cov.: 38 AF XY: 0.00000275 AC XY: 2 AN XY: 727080

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.000112 AC: 5 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26126

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53276

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111848

Other (OTH) AF: 0.00 AC: 0 AN: 60376

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions as Germline

Significance: Pathogenic/Likely pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
1	-	-	Actin accumulation myopathy (1)
1	-	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.75
Mutation Taster		=5/195	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs753923758; hg19: chr1-229568778;