NM_000256.3:c.926+1G>A

Variant names:

• chr11-47346626-C-T
• rs767239679
• NM_000256.3:c.926+1G>A

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PVS1_Moderate PP5

The NM_000256.3(MYBPC3):​c.926+1G>A variant causes a splice donor, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000903 in 1,440,132 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000090 (0 hom.)
• Consequence: MYBPC3 NM_000256.3 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:2
• Conservation: PhyloP100: 1.83
• Publications: 2 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: Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae)
• left ventricular noncompaction 10

  Inheritance: AR, AD 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
• atrial fibrillation

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
• dilated cardiomyopathy

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.004705882 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PP5: Variant 11-47346626-C-T is Pathogenic according to our data. Variant chr11-47346626-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 517283.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MYBPC3	NM_000256.3	c.926+1G>A		splice_donor_variant, intron_variant	Intron 11 of 34	ENST00000545968.6	NP_000247.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MYBPC3	ENST00000545968.6	c.926+1G>A		splice_donor_variant, intron_variant	Intron 11 of 34	5	NM_000256.3	ENSP00000442795.1
MYBPC3	ENST00000399249.6	c.926+1G>A		splice_donor_variant, intron_variant	Intron 10 of 33	5		ENSP00000382193.2
MYBPC3	ENST00000544791.1	n.926+1G>A		splice_donor_variant, intron_variant	Intron 11 of 26	5		ENSP00000444259.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD2 exomes AF: 0.0000130 AC: 3 AN: 231142 AF XY: 0.0000239

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000903 AC: 13 AN: 1440132 Hom.: 0 Cov.: 38 AF XY: 0.0000126 AC XY: 9 AN XY: 715058

African (AFR) AF: 0.00 AC: 0 AN: 32734

American (AMR) AF: 0.00 AC: 0 AN: 41586

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 24624

East Asian (EAS) AF: 0.00 AC: 0 AN: 39474

South Asian (SAS) AF: 0.000156 AC: 13 AN: 83400

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52742

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5652

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1100502

Other (OTH) AF: 0.00 AC: 0 AN: 59418

GnomAD4 genome Cov.: 31

Alfa AF: 0.0000854 Hom.: 0

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1

Jul 18, 2024

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Identified in a fetus with hypertrophic cardiomyopathy who also harbored a variant in the VCL gene (PMID: 34321787); Canonical splice site variant predicted to result in an in-frame loss of the adjacent exon in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 31447099, 33087929, 34321787) -

Hypertrophic cardiomyopathy Pathogenic:1

Aug 05, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects a donor splice site in intron 11 of the MYBPC3 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in MYBPC3 are known to be pathogenic (PMID: 19574547). This variant is present in population databases (rs767239679, ExAC 0.02%). Disruption of this splice site has been observed in individual(s) with dilated cardiomyopathy (Invitae). ClinVar contains an entry for this variant (Variation ID: 517283). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

not specified Uncertain:1

Aug 14, 2019

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant classified as Uncertain Significance - Favor Pathogenic. The c.926+1G>A variant in MYBPC3 has not been previously reported in individuals with cardiomyopathy but has been identified in 3/27668 of South Asian chromosomes by gnomAD (http://gnomad.broadinstitute.org). This variant occurs in the invariant region (+/- 1,2) of the splice consensus sequence and is predicted to cause altered splicing leading to an abnormal or absent protein. In summary, while there is some suspicion for a pathogenic role, the clinical significance of this variant is uncertain. ACMG/AMP Criteria applied: PVS1_Moderate, PP3. -

Cardiomyopathy Uncertain:1

Feb 11, 2025

Color Diagnostics, LLC DBA Color Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant causes a C>T nucleotide substitution at the +1 position of intron 11 of the MYBPC3 gene. Splice site prediction tools predict that this variant may have a significant impact on RNA splicing. Because this variant alters the canonical splice donor site, it is expected to cause an in-frame skipping of 27 nucleotides (9 amino acids). To our knowledge, functional studies have not been performed for this variant. This variant has not been reported in individuals affected with MYBPC3-related disorders in the literature. This variant has been identified in 3/231142 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.022	T
BayesDel_noAF	Uncertain	-0.050
CADD	Pathogenic	26
DANN	Benign	0.96
Eigen	Pathogenic	0.79
Eigen_PC	Uncertain	0.56
FATHMM_MKL	Benign	0.75	D
PhyloP100		1.8
GERP RS		4.2
Mutation Taster		=2/98	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.76
SpliceAI score (max)		0.45		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.45		Position offset: 1

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

Other links and lift over

dbSNP: rs767239679; hg19: chr11-47368177;