19-55132966-G-C

Position:

• chr19-55132966-G-C

Variant summary

Our verdict is Likely benign. Variant got -4 ACMG points: 0P and 4B. BP4_Strong

The NM_003283.6(TNNT1):​c.792-6C>G variant causes a splice region, splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000131 in 1,447,046 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000013 (0 hom.)
• Consequence: TNNT1 NM_003283.6 splice_region, splice_polypyrimidine_tract, intron
• Scores: Splicing: ADA: 0.002599
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.252

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]

ACMG classification

Verdict is Likely_benign. Variant got -4 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.69).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TNNT1	NM_003283.6	c.792-6C>G		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		ENST00000588981.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TNNT1	ENST00000588981.6	c.792-6C>G		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		1	NM_003283.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.0000131 AC: 19 AN: 1447046 Hom.: 0 Cov.: 31 AF XY: 0.0000125 AC XY: 9 AN XY: 718300

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: 0.0000194

Gnomad4 NFE exome AF: 0.0000136

Gnomad4 OTH exome AF: 0.0000501

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000468 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Nemaline myopathy 5 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 29, 2022

This sequence change falls in intron 13 of the TNNT1 gene. It does not directly change the encoded amino acid sequence of the TNNT1 protein. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This variant has not been reported in the literature in individuals affected with TNNT1-related conditions. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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
BayesDel_noAF	Benign	-0.69
CADD	Benign	11
DANN	Benign	0.83

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.0026
dbscSNV1_RF	Benign	0.15
SpliceAI score (max)		0.27		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.27		Position offset: -6

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs753081977; hg19: chr19-55644334;