rs1553248513

Positions:

• chr1-154170415-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 5P and 1B. PM1 PM2 PP2 BP4

The NM_152263.4(TPM3):​c.760A>G​(p.Ile254Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,880 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign 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. I254T) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: TPM3 NM_152263.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.98

Genes affected

TPM3 (HGNC:12012): (tropomyosin 3) This gene encodes a member of the tropomyosin family of actin-binding proteins. Tropomyosins are dimers of coiled-coil proteins that provide stability to actin filaments and regulate access of other actin-binding proteins. Mutations in this gene result in autosomal dominant nemaline myopathy and other muscle disorders. This locus is involved in translocations with other loci, including anaplastic lymphoma receptor tyrosine kinase (ALK) and neurotrophic tyrosine kinase receptor type 1 (NTRK1), which result in the formation of fusion proteins that act as oncogenes. There are numerous pseudogenes for this gene on different chromosomes. Alternative splicing results in multiple transcript variants. [provided by RefSeq, May 2013]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a chain Tropomyosin alpha-3 chain (size 283) in uniprot entity TPM3_HUMAN there are 54 pathogenic changes around while only 2 benign (96%) in NM_152263.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, TPM3
• BP4: Computational evidence support a benign effect (MetaRNN=0.34073615).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TPM3	NM_152263.4	c.760A>G	p.Ile254Val	missense_variant	8/10	ENST00000651641.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TPM3	ENST00000651641.1	c.760A>G	p.Ile254Val	missense_variant	8/10		NM_152263.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461880 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727242

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 0.00000270

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Congenital myopathy with fiber type disproportion;C5829889:Congenital myopathy 4B, autosomal recessive Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jul 26, 2022

This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 254 of the TPM3 protein (p.Ile254Val). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TPM3-related conditions. ClinVar contains an entry for this variant (Variation ID: 531179). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C25"). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.17
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Uncertain	0.11
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Benign	0.24	T;.;.;D;.;.;.;.;.;.;D
Eigen	Benign	0.13
Eigen_PC	Uncertain	0.25
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.86	D;T;D;D;.;D;T;D;T;T;D
M_CAP	Benign	0.023	T
MetaRNN	Benign	0.34	T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Pathogenic	0.80	D
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;D
PrimateAI	Pathogenic	0.82	D
Sift4G	Benign	0.60	T;T;T;T;T;T;T;T;T;T;T
Polyphen		0.20, 0.077	.;B;.;.;.;.;.;.;B;.;.
Vest4		0.44
MVP		0.89
MPC		0.96
ClinPred		0.63	D
GERP RS		4.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.8
Varity_R		0.15

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: rs1553248513; hg19: chr1-154142891;