19-55132948-T-G

Variant names:

• chr19-55132948-T-G
• rs1365147328
• NM_003283.6:c.804A>C

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 2P and 7B. PM2 BP4_Strong BP6_Moderate BP7

The NM_003283.6(TNNT1):​c.804A>C​(p.Ala268Ala) 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. Variant has been reported in ClinVar as Likely benign (★). Synonymous variant affecting the same amino acid position (i.e. A268A) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TNNT1 NM_003283.6 synonymous
• Clinical Significance: Likely benign criteria provided, single submitter B:1
• Conservation: PhyloP100: -0.718
• Publications: 0 publications found

Genes affected

TNNT1 (HGNC:11948): (troponin T1, slow skeletal type) This gene encodes a protein that is a subunit of troponin, which is a regulatory complex located on the thin filament of the sarcomere. This complex regulates striated muscle contraction in response to fluctuations in intracellular calcium concentration. This complex is composed of three subunits: troponin C, which binds calcium, troponin T, which binds tropomyosin, and troponin I, which is an inhibitory subunit. This protein is the slow skeletal troponin T subunit. Mutations in this gene cause nemaline myopathy type 5, also known as Amish nemaline myopathy, a neuromuscular disorder characterized by muscle weakness and rod-shaped, or nemaline, inclusions in skeletal muscle fibers which affects infants, resulting in death due to respiratory insufficiency, usually in the second year. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]

TNNT1 Gene-Disease associations (from GenCC):

• nemaline myopathy 5

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Ambry Genetics, ClinGen, Labcorp Genetics (formerly Invitae)
• nemaline myopathy

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen
• nemaline myopathy 5C, autosomal dominant

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_benign. The variant received -5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.5).
• BP6: Variant 19-55132948-T-G is Benign according to our data. Variant chr19-55132948-T-G is described in ClinVar as [Likely_benign]. Clinvar id is 1614241.Status of the report is criteria_provided_single_submitter, 1 stars.
• BP7: Synonymous conserved (PhyloP=-0.718 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TNNT1	NM_003283.6	c.804A>C	p.Ala268Ala	synonymous_variant	Exon 14 of 14	ENST00000588981.6	NP_003274.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TNNT1	ENST00000588981.6	c.804A>C	p.Ala268Ala	synonymous_variant	Exon 14 of 14	1	NM_003283.6	ENSP00000467176.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely benign

Submissions summary: Benign:1

Revision: criteria provided, single submitter

Submissions by phenotype

Nemaline myopathy 5 Benign:1

Oct 30, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.50
CADD	Benign	11
DANN	Benign	0.80
PhyloP100		-0.72

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: rs1365147328; hg19: chr19-55644316;