11-47346319-CC-AA

Variant names:

• chr11-47346319-CC-AA
• NM_000256.3:c.977_978delGGinsTT
• MYBPC3 p.Arg326Leu

GermlineCancer (beta)

Variant summary

Our verdict is Uncertain significance.

+2 Uncertain · Warm

-7

-6

-1

0

+5

+6

+9

+10

BenignB

Likely BenignLB

UncertainVUS

Likely PathogenicLP

PathogenicP

The variant received 2 classification points (ACGS-UK Somatic Oncogenicity v2025). O3_Moderate

The NM_000256.3(MYBPC3):c.977_978delGGinsTT (p.Arg326Leu) variant causes a missense change. Note: allele frequency estimates from gnomAD may be inaccurate for this variant type (MNP or indel longer than 3 bp) due to technology limitations. The variant is absent from the gnomAD population database at sites with sufficient sequencing coverage. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Other variants at the same amino acid position have been reported in ClinVar (not pathogenic): p.R326Q: Benign/Likely_benign (ClinVar VariationId 42813, 2 stars); p.R326= (synonymous): Likely_benign (ClinVar VariationId 1535531, 1 star); p.R326W: Uncertain_significance (ClinVar VariationId 525027, 2 stars)

• Frequency: Genomes: not found (cov: 32)
• Consequence: MYBPC3 NM_000256.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.16
• Publications: 0 publications found

Genes affected

MYBPC3 (HGNC:7551): (myosin binding protein C3) MYBPC3 encodes the cardiac isoform of myosin-binding protein C. Myosin-binding protein C is a myosin-associated protein found in the cross-bridge-bearing zone (C region) of A bands in striated muscle. MYBPC3 is expressed exclusively in heart muscle and is a key regulator of cardiac contraction. Mutations in this gene are a frequent cause of familial hypertrophic cardiomyopathy. [provided by RefSeq, May 2022]

MYBPC3 Gene-Disease associations (from GenCC):

• hypertrophic cardiomyopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• hypertrophic cardiomyopathy 4

  Inheritance: AD, AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• left ventricular noncompaction 10

  Inheritance: AD, AR Classification: DEFINITIVE, MODERATE, LIMITED Submitted by: Ambry Genetics
• familial isolated dilated cardiomyopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• arrhythmogenic right ventricular cardiomyopathy

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen, G2P
• atrial fibrillation

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
• congenital heart disease

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen
• dilated cardiomyopathy

  Inheritance: AD, AR Classification: LIMITED Submitted by: ClinGen
• familial dilated cardiomyopathy

  Inheritance: AD Classification: LIMITED Submitted by: G2P

Classification according to ACGS-UK Somatic Oncogenicity v2025

Specifications for MYBPC3 are available in the ClinGen Criteria Specification Registry and recommended for reference when assigning criteria.

Classification was made for transcript:

Our verdict: Uncertain_significance. The variant received 2 points.

Apply	Criterion Code & Title / Strength	Strength	Rationale / Clinical Context
	O3Absent or very rare in population		Absent or extremely rare in gnomAD (AC ≤ 2) — O3 moderate; GnomAD: AF = absent, AC = 0 — absent/extremely rare (O3 moderate [+2])

Variant Effect in Transcripts

Automated classification analysis was done for transcript: NM_000256.3. You can select a different transcript below to see updated classification assignments.

RefSeq Transcripts

Sel.	Gene / Transcript	Tags	HGVSc / HGVSp	Effect	Exon rank	Protein / UniProt
	MYBPC3 NM_000256.3	MANE Select	c.977_978delGGinsTT p.Arg326Leu	missense	N/A	Prot: NP_000247.2 UniProt:

MYBPC3 NM_000256.3

MANE Select

HGVSc / HGVSpc.977_978delGGinsTTp.Arg326Leu

Exon rankN/A

missense

Prot: NP_000247.2UniProt: Q14896-1A5YM48

Ensembl Transcripts

Sel.	Gene / Transcript	Tags	HGVSc / HGVSp	Effect	Exon rank	Protein / UniProt
	MYBPC3 ENST00000545968.6	TSL:5MANE Select	c.977_978delGGinsTT p.Arg326Leu	missense	N/A	Prot: ENSP00000442795.1 UniProt:
	MYBPC3 ENST00000399249.6	TSL:5	c.977_978delGGinsTT p.Arg326Leu	missense	N/A	Prot: ENSP00000382193.2 UniProt:
	MYBPC3 ENST00000544791.1	TSL:5	n.977_978delGGinsTT	non_coding_transcript_exon	Exon 12 of 27	Prot: ENSP00000444259.1 UniProt:

MYBPC3 ENST00000545968.6

TSL:5MANE Select

HGVSc / HGVSpc.977_978delGGinsTTp.Arg326Leu

Exon rankN/A

missense

Prot: ENSP00000442795.1UniProt: Q14896-1

MYBPC3 ENST00000399249.6

TSL:5

HGVSc / HGVSpc.977_978delGGinsTTp.Arg326Leu

Exon rankN/A

missense

Prot: ENSP00000382193.2UniProt: A8MXZ9

MYBPC3 ENST00000544791.1

TSL:5

HGVSc / HGVSpn.977_978delGGinsTT

Exon rankExon 12 of 27

non_coding_transcript_exon

Prot: ENSP00000444259.1UniProt: F5GZR4

Frequencies

Allele frequencies (AF), counts (AC/AN), homozygotes and coverage

Common (AF > 0.05 / Hom > 5)

Rare (AF ≤ 0.0001 / Hom ≤ 1)

Source / population	AF	AC	Hom	AN	Coverage
Global population databases 2 sources Large-scale international reference populations
GnomAD3 genomes	AF:	AC:	Hom:	AN:	Cov:32
GnomAD4 genome	AF:	AC:	Hom:	AN:	Cov:32

Showing 2 sources

ClinVar

Not reported in ClinVar

Computational Scores

Algorithm	Calibrated pred.	Score	Prediction
PhyloP100	Benign	1.2

Showing 1 of 1 scores

Splicing Scores

No splicing scores have been computed for this variant.

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

MaveDB functional evidence

MaveDB is a public repository of laboratory assays that test the effect of thousands of variants at once — treat this as supporting research data and interpret it with great caution; it is not a clinical classification.

No MaveDB functional evidence found for this variant.

Other links and lift over

hg19: chr11-47367870;

ACMG debug oncogenicity

ACGS debug oncogenicity

ACMG debug germline

Submit to ClinVar