11-1938477-C-A

Variant names:

• chr11-1938477-C-A
• NM_006757.4:c.762C>A
• TNNT3 p.Gly254Gly

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM2 BP4_Moderate BP7

The NM_006757.4(TNNT3):​c.762C>A​(p.Gly254Gly) variant causes a synonymous 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. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. G254G) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TNNT3 NM_006757.4 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -4.71
• Publications: 0 publications found

Genes affected

TNNT3 (HGNC:11950): (troponin T3, fast skeletal type) The binding of Ca(2+) to the trimeric troponin complex initiates the process of muscle contraction. Increased Ca(2+) concentrations produce a conformational change in the troponin complex that is transmitted to tropomyosin dimers situated along actin filaments. The altered conformation permits increased interaction between a myosin head and an actin filament which, ultimately, produces a muscle contraction. The troponin complex has protein subunits C, I, and T. Subunit C binds Ca(2+) and subunit I binds to actin and inhibits actin-myosin interaction. Subunit T binds the troponin complex to the tropomyosin complex and is also required for Ca(2+)-mediated activation of actomyosin ATPase activity. There are 3 different troponin T genes that encode tissue-specific isoforms of subunit T for fast skeletal-, slow skeletal-, and cardiac-muscle. This gene encodes fast skeletal troponin T protein; also known as troponin T type 3. Alternative splicing results in multiple transcript variants encoding additional distinct troponin T type 3 isoforms. A developmentally regulated switch between fetal/neonatal and adult troponin T type 3 isoforms occurs. Additional splice variants have been described but their biological validity has not been established. Mutations in this gene may cause distal arthrogryposis multiplex congenita type 2B (DA2B). [provided by RefSeq, Oct 2009]

TNNT3 Gene-Disease associations (from GenCC):

• arthrogryposis, distal, type 2B2

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: PanelApp Australia, Ambry Genetics
• distal arthrogryposis type 2B1

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• congenital myopathy

  Inheritance: AR Classification: STRONG Submitted by: G2P
• nemaline myopathy

  Inheritance: AR Classification: MODERATE, LIMITED Submitted by: ClinGen, Ambry Genetics
• digitotalar dysmorphism

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Sheldon-hall syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_benign. The variant received -1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.44).
• BP7: Synonymous conserved (PhyloP=-4.71 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_006757.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TNNT3	NM_006757.4	MANE Select	c.762C>A	p.Gly254Gly	synonymous	Exon 16 of 16	NP_006748.1	P45378-2
	TNNT3	NM_001367846.1		c.795C>A	p.Gly265Gly	synonymous	Exon 18 of 18	NP_001354775.1	P45378-1
	TNNT3	NM_001363561.2		c.771C>A	p.Gly257Gly	synonymous	Exon 17 of 17	NP_001350490.1	P45378-3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TNNT3	ENST00000278317.11	TSL:5 MANE Select	c.762C>A	p.Gly254Gly	synonymous	Exon 16 of 16	ENSP00000278317.6	P45378-2
	TNNT3	ENST00000381589.7	TSL:1	c.756C>A	p.Gly252Gly	synonymous	Exon 16 of 16	ENSP00000371001.3	P45378-6
	TNNT3	ENST00000381579.7	TSL:1	c.738C>A	p.Gly246Gly	synonymous	Exon 15 of 15	ENSP00000370991.3	P45378-4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.44
CADD	Benign	1.6
DANN	Benign	0.76
PhyloP100		-4.7

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

hg19: chr11-1959707;