rs1553248522

Positions:

• chr1-154170438-G-A
• chr1-154170438-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP2

The NM_152263.4(TPM3):​c.737C>T​(p.Ser246Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: TPM3 NM_152263.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 8.12

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]

TPM3 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_152263.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TPM3. . Gene score misZ 2.3546 (greater than the threshold 3.09). Trascript score misZ 3.2484 (greater than threshold 3.09). GenCC has associacion of gene with congenital generalized hypercontractile muscle stiffness syndrome, intermediate nemaline myopathy, congenital myopathy 4B, autosomal recessive, cap myopathy, congenital fiber-type disproportion myopathy, congenital myopathy 4A, autosomal dominant, TPM3-related myopathy, childhood-onset nemaline myopathy.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TPM3	NM_152263.4	c.737C>T	p.Ser246Leu	missense_variant	8/10	ENST00000651641.1	NP_689476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TPM3	ENST00000651641.1	c.737C>T	p.Ser246Leu	missense_variant	8/10		NM_152263.4	ENSP00000498577.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

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

Labcorp Genetics (formerly Invitae), Labcorp

Oct 09, 2023

This sequence change replaces serine, which is neutral and polar, with leucine, which is neutral and non-polar, at codon 246 of the TPM3 protein (p.Ser246Leu). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with clinical features of congenital myopathy (Invitae). ClinVar contains an entry for this variant (Variation ID: 531178). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt TPM3 protein function. 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. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Oct 29, 2020

Not observed in large population cohorts (Lek et al., 2016); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.79
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.25
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Benign	0.41	T;.;.;D;.;.;.;.;.;.;D
Eigen	Uncertain	0.45
Eigen_PC	Uncertain	0.52
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.75	T;T;T;T;.;T;T;T;T;T;T
M_CAP	Benign	0.073	D
MetaRNN	Uncertain	0.52	D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.24	D
MutationAssessor	Pathogenic	2.9	.;.;.;.;.;.;.;.;.;.;M
PrimateAI	Pathogenic	0.88	D
PROVEAN	Uncertain	-4.2	.;D;D;D;.;D;D;D;D;D;D
REVEL	Pathogenic	0.76
Sift	Benign	0.033	.;D;D;D;.;D;D;D;D;D;D
Sift4G	Benign	0.085	T;T;T;T;T;T;T;T;T;T;T
Polyphen		0.040, 0.0040	.;B;.;.;.;.;.;.;B;.;.
Vest4		0.55
MVP		0.90
MPC		1.8
ClinPred		0.99	D
GERP RS		4.8
Varity_R		0.51

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: rs1553248522; hg19: chr1-154142914;