NM_006757.4:c.636T>G

Variant names:

• chr11-1934874-T-G
• rs16927166
• NM_006757.4:c.636T>G

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_006757.4(TNNT3):​c.636T>G​(p.Ile212Met) variant causes a missense 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. 16/22 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I212T) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TNNT3 NM_006757.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -1.99
• Publications: 7 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):

• distal arthrogryposis type 2B1

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

  Inheritance: AR Classification: STRONG Submitted by: G2P
• arthrogryposis, distal, type 2B2

  Inheritance: AD Classification: MODERATE Submitted by: Ambry Genetics
• nemaline myopathy

  Inheritance: AR Classification: MODERATE, LIMITED Submitted by: Ambry Genetics, ClinGen
• 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 -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.060902894).

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TNNT3	NM_006757.4	MANE Select	c.636T>G	p.Ile212Met	missense	Exon 14 of 16	NP_006748.1
	TNNT3	NM_001367846.1		c.669T>G	p.Ile223Met	missense	Exon 16 of 18	NP_001354775.1
	TNNT3	NM_001363561.2		c.645T>G	p.Ile215Met	missense	Exon 15 of 17	NP_001350490.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TNNT3	ENST00000278317.11	TSL:5 MANE Select	c.636T>G	p.Ile212Met	missense	Exon 14 of 16	ENSP00000278317.6
	TNNT3	ENST00000381589.7	TSL:1	c.630T>G	p.Ile210Met	missense	Exon 14 of 16	ENSP00000371001.3
	TNNT3	ENST00000381579.7	TSL:1	c.612T>G	p.Ile204Met	missense	Exon 13 of 15	ENSP00000370991.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 179

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.071
BayesDel_addAF	Benign	-0.13	T
BayesDel_noAF	Benign	-0.43
CADD	Benign	0.0010
DANN	Benign	0.87
DEOGEN2	Benign	0.26	T
Eigen	Benign	-1.8
Eigen_PC	Benign	-2.0
FATHMM_MKL	Benign	0.042	N
LIST_S2	Benign	0.79	T
M_CAP	Benign	0.028	D
MetaRNN	Benign	0.061	T
MetaSVM	Benign	-0.97	T
MutationAssessor	Benign	0.0	N
PhyloP100		-2.0
PrimateAI	Uncertain	0.51	T
PROVEAN	Benign	0.14	N
REVEL	Benign	0.23
Sift	Uncertain	0.0080	D
Sift4G	Uncertain	0.035	D
Polyphen		0.027	B
Vest4		0.089
MutPred		0.20		Gain of disorder (P = 0.0563)
MVP		0.45
MPC		0.35
ClinPred		0.17	T
GERP RS		-8.6
Varity_R		0.069
gMVP		0.39
Mutation Taster		=87/13	polymorphism

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

Other links and lift over

dbSNP: rs16927166; hg19: chr11-1956104;