PMID:30565988

Gene:TNNT2

HGNC ID:11949

Case#:A 65-year-old woman with severe hypertrophic cardiomyopathy

DiseaseAssertion:Severe hypertrophic cardiomyopathy

FamilyInfo:no information reported

ParentalTesting:no parental testing reported

CasePresentingHPOs:HP:0001639

CaseHPOFreeText: gene panel testing that identified a single variant

CaseNotHPOs: not found

CaseNotHPOFreeText: not found

CasePreviousTesting: gene panel testing that identified a single variant

Genotyping Method:clinical gene panel testing

FunctionalAnalysis: rapid insertion of TNNT2 gene variants into induced pluripotent stem cell-differentiated cardiomyocytes (iPSC-CMs) for functional annotation of the variants for (E251D)(Figure B)

Variant:c.753G>T (p.Glu251Asp)

ClinVar:not found

CAID:CA090003

gnomAD:not found

AdditionalInfo:not reported

PMID:41969674

Gene:TNNT2

HGNC ID:11949

Case#:male, 41, DCM

DiseaseAssertion:dilated cardiomyopathy

FamilyInfo:The proband reported that his mother died suddenly at approximately 35 years of age (specific cause unknown). Other family members were healthy with no history of cardiac disease. Written informed consent was obtained from all participants.

ParentalTesting:no parental testing reported. Sanger sequencing of available family members (daughter, half-brother, maternal uncle and maternal aunt) confirmed that none carried the variant, supporting its de novo origin

CasePresentingHPOs:HP:0002875, HP:0001644, HP:4000141, HP:6000313

CaseHPOFreeText: ECG showed sinus bradycardia, occasional atrial premature beats, delayed atrioventricular conduction, left atrial enlargement, left ventricular high voltage, incomplete right bundle branch block, and ST-T changes (Figure 1C). CMR revealed late gadolinium enhancement (LGE) in the basal to mid-septal and anterolateral segments of the left ventricle (Figure 1D).

CaseNotHPOs:HP:0000822, HP:0003077

CaseNotHPOFreeText:He denied a history of hyperlipidemia, hypertension, or substance abuse.

CasePreviousTesting:No reports of previous testing

Genotyping Method:whole-exome sequencing and Sanger sequencing

FunctionalAnalysis:not reported

Variant:c.547C>T p.Arg183Trp

ClinVar:43628

CAID:CA004294

gnomAD:Overall allele frequency: 0.000001239

AdditionalInfo:not reported

Case#:a 40-year-old woman with a history of hypokinetic-dilative cardiomyopathy and heterozygous for TNNT2 gene mutation

DiseaseAssertion:hypokinetic-dilative cardiomyopathy

FamilyInfo: her family appreciated the clear communication, and as her condition improved without further complications, she expressed gratitude for the care provided.

ParentalTesting:n/a

CasePresentingHPOs:HP:0001644, HP:0002094, HP:0002094, HP:0001695,

CaseHPOFreeText:Progressive dyspnea and fatigue began in January 2017. In February 2018, the patient had cardiac arrest due to ventricular fibrillation at 26 weeks’ gestation, followed by emergency caesarean section. She carried a heterozygous TNNT2 variant (c.547C>T, p.Arg183Trp)

CaseNotHPOs: HP:0031972, HP:0031972

CaseNotHPOFreeText:Coronary angiography showed no significant stenosis.

CasePreviousTesting:Testing method and scope

Genotyping Method:n/a

FunctionalAnalysis:not reported

Variant: c.547C>T p.Arg183Trp)

Clinvar:not known

CAID:CA391630526

gnomAD:n/a

AdditionalInfo:n/a

PMID:39905734

Gene:TNNT2

HGNC ID:11949

Case#: a 50‐year‐old male who was clinically diagnosed with isolated CS and prescribed with prednisolone without much effect, and subsequent genetic analysis revealed pathogenic variants in LMNA and TNNT2, representative genes for cardiomyopathy.

DiseaseAssertion:Dilated cardiomyopathy

FamilyInfo: not reported

ParentalTesting: He had no family history of heart disease or sudden death

CasePresentingHPOs:HP:0002094,HP:0005110,HP:0025169, HP:0005110

CaseHPOFreeText:Progressive cardiac conduction disease: first-degree AV block with left axis deviation on an earlier ECG progressed to high-grade and then complete AV block. At age 50, the patient also had mild dyspnoea on exertion (New York Class ll) and atrial fibrillation. The authors later stated that it was dilated cardiomyopathy.

CaseNotHPOs:HP:0033608,HP:0002716

CaseNotHPOFreeText:CT showed no enlarged lymph nodes, pulmonary nodules, or other organ abnormalities

CasePreviousTesting: whole‐exome sequencing analysis to evaluate the risk of inherited cardiomyopathies and identified two missense variants in TNNT2 (chr1:201364335(hg38), NM_001001430.3, c.422G>A, p.Arg141Gln) and LMNA (chr1:156136096(hg38), NM_170707.4, c.1132A>C, p.Lys378Gln) (Figure 3). Sanger sequencing analysis identified a heterozygous single‐base substitution (c.1132A>C) in the LMNA gene and c.422G>A in the TNNT2 gene (red arrows).

Genotyping Method:Whole-exome sequencing (WES) identified the variants; Sanger sequencing of the TNNT2 and LMNA variants is shown in Figure 3.

FunctionalAnalysis:Not reported

Variant:TNNT2: NM_001001430.3:c.422G>A (p.Arg141Gln),LMNA: NM_170707.4:c.1132A>C (p.Lys378Gln)

ClinVar:43637

CAID:CA004540

gnomAD:not reported

AdditionalInfo:not reported

PMID:20973921

Gene:TNNT2

HGNC ID:11949

Case#:A 70‐year‐old woman, previously healthy with a left ventricular ejection fraction presented with DCM

DiseaseAssertion:dilated cardiomyopathy and a 4-month history of progressive heart failure

FamilyInfo:"Family history was negative for IDC or heart failure (Figure 3), although an uncle (II‐3) reportedly had an enlarged heart, and three other relatives (II‐1, II‐2, and III‐4) had cardiac related deaths confirmed by death certificate. The proband’s father (II‐1) died of myocardial failure and pulmonary edema; her mother (II‐2) died of pulmonary embolism; and her sister (III‐4) died suddenly of coronary artery disease in her 60s. Her daughter, the proband’s niece (IV‐3), had a history of palpitations and lower extremity swelling, intermittent numbness, and blanching of the fingers at age 49. Her echocardiogram was normal. Her ECG showed nonspecific ST‐T wave changes and left anterior hemiblock."

ParentalTesting:no parental testing reported because both parents were deceased. The two offsprings that were reported were tested and carried both variants.

CasePresentingHPOs:HP:0001644, HP:0001635, HP:0002875, HP:0012378

CaseHPOFreeText:symptoms of progressive dyspnea on exertion and fatigue that began 2–3 months prior to her presentation. Also, she had an unrelenting progression of symptoms and was hospitalized with advanced NYHA Class IV heart failure 6 weeks later. Lastly, she received a heart transplant.

CaseNotHPOs:not reported

CaseNotHPOFreeText:no myocarditis or infiltrative process and no histological evidence of hemochromatosis,

CasePreviousTesting:Oligonucleotide hybridization‐based DNA sequencing was conducted in the proband for a panel of 19 DCM genes ( Table 1 )

Genotyping Method:Oligonucleotide hybridization‐based DNA sequencing and genomic DNA was extracted from whole blood and was sequenced in our laboratory in both directions to detect and/or confirm nucleotide variants in TNNT2 in the proband and the proband’s relatives using an Applied Biosystems 3130XL capillary sequencer

FunctionalAnalysis:R139H (Figure 4): Functional studies in porcine cardiac skinned fibers reconstituted with the mutant R139H troponin T protein showed decreased Ca2+ sensitivity at pH 7, characteristic of DCM.

Variant:416G>A (R139H) in exon 10 and 690–6G>A in intron 13.

ClinVar:not found

CAID:CA004513

gnomAD:not found

AdditionalInfo:not reported