19-55147121-C-T

Variant names:

• chr19-55147121-C-T
• rs1555859876
• NM_003283.6:c.32+5G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM2 PP3_Strong PP5

The NM_003283.6(TNNT1):​c.32+5G>A variant causes a splice region, intron 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. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 32)
• Consequence: TNNT1 NM_003283.6 splice_region, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 2.39
• 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, ClinGen, Labcorp Genetics (formerly Invitae), Ambry Genetics
• nemaline myopathy 5B, autosomal recessive, childhood-onset

  Inheritance: AR Classification: STRONG Submitted by: PanelApp Australia
• nemaline myopathy

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

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

ACMG classification

Our verdict: Likely_pathogenic. The variant received 7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 19-55147121-C-T is Pathogenic according to our data. Variant chr19-55147121-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 465995.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_003283.6. 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
	TNNT1	NM_003283.6	MANE Select	c.32+5G>A		splice_region intron	N/A	NP_003274.3
	TNNT1	NM_001126132.3		c.32+5G>A		splice_region intron	N/A	NP_001119604.1	P13805-3
	TNNT1	NM_001126133.3		c.32+5G>A		splice_region intron	N/A	NP_001119605.1	P13805-2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TNNT1	ENST00000588981.6	TSL:1 MANE Select	c.32+5G>A		splice_region intron	N/A	ENSP00000467176.1	P13805-1
	TNNT1	ENST00000291901.12	TSL:1	c.32+5G>A		splice_region intron	N/A	ENSP00000291901.8	P13805-3
	TNNT1	ENST00000356783.9	TSL:1	c.32+5G>A		splice_region intron	N/A	ENSP00000349233.4	P13805-2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	1	-	Inborn genetic diseases (1)
1	-	-	Nemaline myopathy 5 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.42
CADD	Benign	23
DANN	Benign	0.87
PhyloP100		2.4
PromoterAI		-0.14	Neutral

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.96
SpliceAI score (max)		0.94		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.94		Position offset: 5

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

Other links and lift over

dbSNP: rs1555859876; hg19: chr19-55658489;