1-229432190-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3 PP5

The NM_001100.4(ACTA1):c.617-5C>A variant causes a splice region, splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 31)
• Consequence: ACTA1 NM_001100.4 splice_region, splice_polypyrimidine_tract, intron
• Scores: Splicing: ADA: 0.9873
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: -0.521

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 Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, max_spliceai. No scorers claiming Uncertain. Scorers claiming Benign: dbscSNV1_RF.
• PP5: Variant 1-229432190-G-T is Pathogenic according to our data. Variant chr1-229432190-G-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 1051987.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=2, Likely_pathogenic=1}. Variant chr1-229432190-G-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ACTA1	NM_001100.4	c.617-5C>A		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		ENST00000366684.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ACTA1	ENST00000366684.7	c.617-5C>A		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		1	NM_001100.4	P1
ACTA1	ENST00000366683.4	c.617-5C>A		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		5
ACTA1	ENST00000684723.1	c.482-5C>A		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 31

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Aug 13, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Apr 19, 2021	Not observed in large population cohorts (Lek et al., 2016); In silico analysis supports a deleterious effect on splicing; This variant is associated with the following publications: (PMID: 19562689) -

Actin accumulation myopathy Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Invitae

Dec 30, 2021

This sequence change falls in intron 4 of the ACTA1 gene. It does not directly change the encoded amino acid sequence of the ACTA1 protein. This variant is not present in population databases (gnomAD no frequency). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 1051987). This variant has been observed in individuals with autosomal dominant nemaline myopathy (PMID: 19562689; Invitae). It has also been observed to segregate with disease in related individuals. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.84
Cadd	Benign	22
Dann	Benign	0.48

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.99
dbscSNV1_RF	Benign	0.67
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_AG_spliceai		1.0		Position offset: -2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr1-229567937;