Case#: Family 1, individual II-5

DiseaseAssertion: Dilated cardiomyopathy

FamilyInfo: The proband has a family history of DCM. His father and brother also had DCM and died from heart failure at ages 69 and 63 respectively. The disease follows an autosomal dominant inheritance pattern.

ParentalTesting: Want reported, his father had DMC but this article does not confirm genetic testing of his parents.

CasePresentingHPOs: Dilated cardiomyopathy (HP:0001644) & left ventricular systolic dysfunction (HP:0005162)

CaseHPOFreeText: The proband was diagnosed with DCM at age 45 and received medication for heart failure. At the time of the study he was 66 years old. His echocardiogram showed an enlarged left ventricle and reduced heart function with an ejection fraction of 33%.

CaseNotHPOs: NR

CaseNotHPOFreeText: The researchers reported no other structural heart diseases or conditions contributing to DCM in the affected family members, including coronary heart disease, valvular heart disease, viral myocarditis and hypertension.

CasePreviousTesting: ECG, clinical examination and routine laboratory testing were part of the study assessment. The probands echocardiogram showed a left ventricular end diastolic diameter of 63 mm and an ejection fraction of 33%.

Genotyping Method: Genome wide microsatellite screening, genetic linkage analysis, whole exome sequencing and sanger sequencing.

FunctionalAnalysis: Laboratory experiments showed that the KLF13 E144X mutation reduced the proteins ability to activate the heart related genes ACTC1 and MYH7. The mutation also affected DNA binding cooperation with GATA4 and normal nuclear localization.

Variant: KLF13 c.430G >T

Clinvar: NR

CAID: CA391891162

gnomAD: The researchers reported that the variant was absent from gnomAD and other population databases at the time of their study. No numerical allele frequency was provided.

AdditionalInfo: The proband is a male from a 4th generation Chinese family. His KLF13 mutation was associated with familial DCM. the researchers found that the mutation was shared by affected family members and was absent from unaffected family members and 418 unrelated healthy controls.

Case#: Family 2, III-10 47 year old female

DiseaseAssertion: Dilated cardiomyopathy

FamilyInfo: Multiple family members had DCM. The disease followed an autosomal dominant inheritance pattern.

ParentalTesting: NR

CasePresentingHPOs: Dilated cardiomyopathy (HP:0001644)

CaseHPOFreeText:Female aged 47 with DCM. Her left ventricular end diastolic diameter was 57mm and her ejection fraction was 40%.

CaseNotHPOs: NR

CaseNotHPOFreeText: NR

CasePreviousTesting: Echocardiogram and clinical cardiac evaluation.

Genotyping Method: Sanger sequencing of KLF13

FunctionalAnalysis: The E194X mutation reduced the ability of KLF13 to activate ACTC1 and MYH7 and bind their promoters. It also disrupted cooperation with GATA4.

Variant: KLF13 c.580G>T

Clinvar: NR

CAID: NR

gnomAD: The variant was reported as absent from gnomAD at the time of the study.

AdditionalInfo: The mutation was found in affected family members and was absent from 418 unrelated healthy controls.

Case#: Family B, Case IV.2; 8-year-old male; diagnosed at age 6

DiseaseAssertion: Dilated cardiomyopathy (DCM)

FamilyInfo: Positive family history of sudden cardiac death (SCD). The proband's brother (IV.1) died at age 2 of SCD and renal failure. Both parents (III.1 and III.2) were asymptomatic heterozygous carriers of MYL3 c.106G>T. Two unaffected siblings were tested: IV.3 was wild-type and IV.4 was heterozygous (Fig. 1b; Supplementary Fig. S2b).

ParentalTesting: Both parents (III.1 and III.2) were confirmed heterozygous carriers of MYL3 c.106G>T by PCR and bidirectional Sanger sequencing, supporting autosomal recessive inheritance (Supplementary Genetic Findings; Fig. S2b).

CasePresentingHPOs: HP:0001644 (Dilated cardiomyopathy); HP:0000085 (Horseshoe kidney); HP:0005162 (Reduced left ventricular ejection fraction).

CaseHPOFreeText: DCM diagnosed at age 6; heart transplantation performed shortly after diagnosis. Clinical evaluation revealed horseshoe kidney, severe left ventricular dysfunction (LVEF 15–20%), moderate right ventricular dysfunction (TAPSE 9 mm), chamber cardiomegaly on coronary CT angiography, and rapid ventricular tachycardia on ECG (Main text, Family B; Supplementary Results, p. 6).

CaseNotHPOs: NR

CaseNotHPOFreeText: NR

CasePreviousTesting: NR (no prior diagnostic genetic testing reported before the study's exome sequencing)

Genotyping Method: Exome sequencing identified the homozygous MYL3 c.106G>T (p.Glu36Ter) variant in the proband (IV.2). PCR and bidirectional Sanger sequencing validated the variant and confirmed segregation in the parents and two unaffected siblings (Supplementary Methods; Supplementary Genetic Findings; Fig. S2b).

FunctionalAnalysis: Zebrafish cmlc1 knockdown and rescue experiments were performed using human MYL3 RNA containing c.106G>T (p.Glu36Ter). Unlike wild-type MYL3 RNA, the mutant RNA failed to rescue the cardiac phenotype, with persistent cardiac edema, ventricular dysfunction, and atrial dilation (Fig. 2; Supplementary Methods; Supplementary Movie S7).

Variant: MYL3 NM_000258.2:c.106G>T (p. Glu36Ter); homozygous nonsense variant

ClinVar: NR

CAID: CA352499542

gnomAD: NR

AdditionalInfo: The authors classified the homozygous MYL3 c.106G>T (p.Glu36Ter) nonsense variant as pathogenic. The variant introduces a premature termination codon at amino acid 36. The proband was born to asymptomatic, consanguineous (first-cousin) parents of Bakhtiyari ancestry. Family segregation and zebrafish functional studies provide supporting evidence (Supplementary Results; Supplementary Genetic Findings; Supplementary Table S2).

Case1: 6 year old, female

DiseaseAssertion: Restrictive cardiomyopathy

FamilyInfo:Both parents were heterozygous carriers, supporting an autosomal recessive inheritance pattern, younger brother showed no abnormalities or signs of the same illness

ParentalTesting: Sanger Sequencing

CasePresentingHPOs:HP:0002094, HP:0012378

CaseHPOFreeText: well below normal weight and height range for patients age, preserved systolic function and diastolic dysfunction, revealed preserved left ventricular systolic function with an ejection fraction, impaired diastolic function, enlarged atrium, wall thickening, impaired ventricular filling

CaseNotHPOs: NR

CaseNotHPOFreeText: comprehensive initial workup, including blood tests and urinalysis, revealed no additional abnormalities

CasePreviousTesting: Echocardiogram, blood tests, urinalysis

Genotyping Method: Whole-exome sequencing

FunctionalAnalysis: NR

Variant: TNNI3 c.406 C > T:p.R136

ClinVar: 488853

gnomAD: not found

Case1: Male, 65, Chinese DiseaseAssertion: Non‐obstructive HCM, heart failure, and atrial fibrillation FamilyInfo:Family history of HCM and sudden cardiac death CasePresentingHPOs: HP:0031295, HP:0001685, HP:0001712, HP:0012664, HP:0025169, HP:0005110, HP:0001658, HP:0001635 CaseHPOFreeText: Presented with stenosis in the circumflex artery and has a history of non‐obstructive HCM, heart failure NYHA class III, AF, myocardial infarction, and coronary atherosclerosis CasePreviousTesting: Exercise stress echocardiography test, transthoracic echocardiography, electrocardiogram, cardiovascular magnetic resonance (CMR), computerized tomography coronary angiogram, and peripheral blood draw Genotyping Method: Genomic DNA for whole-exome sequencing (WES) by NovaSeq 6000 platform from the peripheral blood draw of proband. FunctionalAnalysis:C to T transition at nucleotide 1522 in coding exon 16 of MYBPC3 replaces the glutamine residue with a premature translational stop signal (p.Gln508Ter) Variant: NM_000256.3:c.1522C>T MANE Select <br /> ClinVar:180941