Case1: Female, 85 at diagnosis, ethnicity not stated

DiseaseAssertion: Hypertrophic cardiomyopathy (HCM)

FamilyInfo: An index patient’s brother (II.6) was reported with moderate HCM and another brother (II.7) with sudden cardiac death at the age of 40 years. The clinical screening led to the diagnosis of HCM in two of the index patient’s descendants, a daughter and a son. Daughter (III.4, age 59) with septal hypertrophy of 16 mm confirmed by cardiac MRI, son (III.8, age 47) with septal hypertrophy of 15 mm. Daughter (III.6, age 50) is an unaffected carrier. Five other relatives (III.1, III.5, III.6, III.7, IV.1) were healthy with normal cardiac evaluation. Pedigree shown in Figure 1.

ParentalTesting: Not preformed.

CasePresentingHPOs: HP:0001639, HP:0001279

CaseHPOFreeText: Admitted to the emergency unit with chest pain after a pre-syncopal episode at the age of 85. Electrocardiogram showed sinus rhythm, negative T waves in V1-V3 and signs of ventricular hypertrophy. Transthoracic echocardiography detected asymmetric septal hypertrophy of 25 mm with preserved ejection fraction, moderate diastolic dysfunction and mild left atrial enlargement. Twenty-four-hour Holter monitoring documented episodes of non-sustained ventricular tachycardia defined as ≥ 3 beats at a rate of ≥ 120 bpm

CaseNotHPOs: NR

CaseNotHPOFreeText: Coronary artery disease was ruled out

CasePreviousTesting: NR

Genotyping Method: The index patient’s genomic DNA was subjected to massively parallel sequencing to identify the genetic origin of the disease using a 251-gene cardiomyopathy diagnostic panel. Targeted massively parallel sequencing of the index patient’s genomic DNA was performed with an Agilent SureSelect custom library covering 251 genes. For the MYBPC3 gene: all exons including the complete sequence of introns. Sequencing performed on NovaSeq 6000 (Illumina), bioinformatics pipeline using BWA alignment and GATK variant calling, reference genome GRCh37/hg19. Sanger sequencing confirmed both variants

FunctionalAnalysis: Minigene and patient blood RNA splicing assays performed. Both the minigene and patients’ RNA splicing assays revealed that the MYBPC3 c.3331−26T>G variant promoted complete intron 30 retention in the mRNA, and also partial retention of the second half of intron 30. Normal MYBPC3 mRNA was not detected in the MUT lanes. The corresponding normal MYBPC3 fusion protein was not detected with either of the two antibodies in cells transfected with the MUT plasmid.

Variant: NM_000256.3:c.3331−26T>G

ClinVar: 1320039

CAID: CA2573146361

gnomAD: chr11-47332999-A-C

AdditionalInfo: This paper also identified two additional unrelated HCM probands carrying c.3331−26T>G in a large cohort of 9,611 HCM probands

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