chr1-236755022-A-T

Position:

• chr1-236755022-A-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_001103.4(ACTN2):​c.1978A>T​(p.Ile660Phe) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,876 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. I660I) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: ACTN2 NM_001103.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.43

Genes affected

ACTN2 (HGNC:164): (actinin alpha 2) Alpha actinins belong to the spectrin gene superfamily which represents a diverse group of cytoskeletal proteins, including the alpha and beta spectrins and dystrophins. Alpha actinin is an actin-binding protein with multiple roles in different cell types. In nonmuscle cells, the cytoskeletal isoform is found along microfilament bundles and adherens-type junctions, where it is involved in binding actin to the membrane. In contrast, skeletal, cardiac, and smooth muscle isoforms are localized to the Z-disc and analogous dense bodies, where they help anchor the myofibrillar actin filaments. This gene encodes a muscle-specific, alpha actinin isoform that is expressed in both skeletal and cardiac muscles. Several transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, May 2013]

ACTN2 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.839

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ACTN2	NM_001103.4	c.1978A>T	p.Ile660Phe	missense_variant	17/21	ENST00000366578.6	NP_001094.1
ACTN2	NM_001278343.2	c.1978A>T	p.Ile660Phe	missense_variant	17/21		NP_001265272.1
ACTN2	NR_184402.1	n.2350A>T		non_coding_transcript_exon_variant	19/23

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ACTN2	ENST00000366578.6	c.1978A>T	p.Ile660Phe	missense_variant	17/21	1	NM_001103.4	ENSP00000355537.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000795 AC: 2 AN: 251468 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135912

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000578

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS 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: 0.00000137 AC: 2 AN: 1461876 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727238

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000447

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Primary familial hypertrophic cardiomyopathy;C2677338:Dilated cardiomyopathy 1AA Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 27, 2016

This sequence change replaces isoleucine with phenylalanine at codon 660 of the ACTN2 protein (p.Ile660Phe). The isoleucine residue is highly conserved and there is a small physicochemical difference between isoleucine and phenylalanine. This variant is present in population databases (rs768670466, ExAC 0.02%) but has not been reported in the literature in individuals with an ACTN2-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C15"). In summary, this variant is a rare missense change with uncertain impact on protein function. There is no indication that it causes disease, but the available evidence is currently insufficient to prove that conclusively. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.47
BayesDel_addAF	Uncertain	0.016	T
BayesDel_noAF	Uncertain	-0.040
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.54	.;.;D
Eigen	Uncertain	0.66
Eigen_PC	Uncertain	0.60
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D;D;D
M_CAP	Benign	0.037	D
MetaRNN	Pathogenic	0.84	D;D;D
MetaSVM	Benign	-0.36	T
MutationAssessor	Uncertain	2.6	.;M;M
PrimateAI	Uncertain	0.75	T
PROVEAN	Uncertain	-3.3	.;D;D
REVEL	Uncertain	0.43
Sift	Uncertain	0.0010	.;D;D
Sift4G	Uncertain	0.020	D;D;D
Polyphen		0.96	.;.;D
Vest4		0.81
MutPred		0.71		.;Loss of MoRF binding (P = 0.1067);Loss of MoRF binding (P = 0.1067);
MVP		0.68
MPC		0.92
ClinPred		0.98	D
GERP RS		4.6
Varity_R		0.78
gMVP		0.75

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

Publications

LitVar

Other links and lift over

dbSNP: rs768670466; hg19: chr1-236918322;