rs121917761

chr19-55154068-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_000363.5(TNNI3):c.511G>A(p.Ala171Thr) variant causes a missense change. The variant allele was found at a frequency of 0.000000685 in 1,460,592 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A171V) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TNNI3 NM_000363.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts P:1 U:2
• Conservation: PhyloP100: 4.81

Genes affected

TNNI3 (HGNC:11947): (troponin I3, cardiac type) Troponin I (TnI), along with troponin T (TnT) and troponin C (TnC), is one of 3 subunits that form the troponin complex of the thin filaments of striated muscle. TnI is the inhibitory subunit; blocking actin-myosin interactions and thereby mediating striated muscle relaxation. The TnI subfamily contains three genes: TnI-skeletal-fast-twitch, TnI-skeletal-slow-twitch, and TnI-cardiac. This gene encodes the TnI-cardiac protein and is exclusively expressed in cardiac muscle tissues. Mutations in this gene cause familial hypertrophic cardiomyopathy type 7 (CMH7) and familial restrictive cardiomyopathy (RCM). Troponin I is useful in making a diagnosis of heart failure, and of ischemic heart disease. An elevated level of troponin is also now used as indicator of acute myocardial injury in patients hospitalized with moderate/severe Coronavirus Disease 2019 (COVID-19). Such elevation has also been associated with higher risk of mortality in cardiovascular disease patients hospitalized due to COVID-19. [provided by RefSeq, Aug 2020]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a hotspot region, there are 9 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 15 uncertain in NM_000363.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.958

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TNNI3	NM_000363.5	c.511G>A	p.Ala171Thr	missense_variant	7/8	ENST00000344887.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TNNI3	ENST00000344887.10	c.511G>A	p.Ala171Thr	missense_variant	7/8	1	NM_000363.5	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460592 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 726642

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: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Cardiomyopathy, familial restrictive, 1 Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Jan 01, 2003

- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Dec 28, 2021

Variant summary: TNNI3 c.511G>A (p.Ala171Thr) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 248984 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.511G>A has been reported in the literature in an individual affected with Restrictive Cardiomyopathy who was an only child and no clinical data or DNA was available on his deceased parents (example, Mogensen_2003). None of his children were identified as carriers of this variant. It has also been reported with a likely pathogenic classification in an individual reportedly affected with hypertrophic cardiomyopathy (HCM) within the Oxford Medical Genetics Laboratories (OMGL) testing cohort (example, Walsh_2017). These report(s) do not provide unequivocal conclusions about association of the variant with Restrcitve/Hypertrophic Cardiomyopathy. At-least two publications report experimental evidence evaluating an impact on protein function (example, Gomes_2005, Yumoto_2005), however, none of these studies allows convincing conclusions about the variant effect. Briefly summarized, this variant demonstrated an increase in Calcium sensitivity of force development compared with WT cTnI, caused a decrease in ability of cTnI to inhibit actomyosin ATPase activity and using mixtures of WT and mutant cTnI, this variant was classified into the dominant group (along with two other variants) in actomyosin ATPase assays in the absence of calcium ion. Most of the mutants were able to activate actomyosin ATPase similarly to wild-type. As represented, the data on this variant do not allow unequivocal contributions to ascertain as a strong evidence surrounding the pathophysiology of disease. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation and classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jan 19, 2023

Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. ClinVar contains an entry for this variant (Variation ID: 12429). This missense change has been observed in individual(s) with restrictive cardiomyopathy or hypertrophic cardiomyopathy (PMID: 12531876, 27532257, 30384889). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 171 of the TNNI3 protein (p.Ala171Thr). Experimental studies have shown that this missense change affects TNNI3 function (PMID: 15961398, 16288990, 18423659). 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
AlphaMissense	Benign	0.17
CardioboostCm	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.26	D
BayesDel_noAF	Pathogenic	0.14
Cadd	Pathogenic	28
Dann	Pathogenic	1.0
DEOGEN2	Pathogenic	0.94	D;D
Eigen	Uncertain	0.47
Eigen_PC	Uncertain	0.43
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Uncertain	0.96	D;D
M_CAP	Pathogenic	0.34	D
MetaRNN	Pathogenic	0.96	D;D
MetaSVM	Pathogenic	0.90	D
MutationAssessor	Uncertain	2.3	M;.
MutationTaster	Benign	1.0	A;A
PrimateAI	Uncertain	0.71	T
PROVEAN	Uncertain	-2.8	D;.
REVEL	Pathogenic	0.80
Sift	Benign	0.042	D;.
Sift4G	Benign	0.11	T;T
Polyphen		0.99	D;.
Vest4		0.69
MutPred		0.84		Loss of helix (P = 0.0376);.;
MVP		0.96
MPC		1.7
ClinPred		0.97	D
GERP RS		3.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.54

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs121917761; hg19: chr19-55665436;