rs730880577

Positions:

• chr11-47335098-G-A
• chr11-47335098-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_000256.3(MYBPC3):​c.2849C>T​(p.Ala950Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000343 in 1,457,304 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A950E) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: MYBPC3 NM_000256.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:6
• Conservation: PhyloP100: 9.51

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.934

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MYBPC3	NM_000256.3	c.2849C>T	p.Ala950Val	missense_variant	27/35	ENST00000545968.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MYBPC3	ENST00000545968.6	c.2849C>T	p.Ala950Val	missense_variant	27/35	5	NM_000256.3	P4
MYBPC3	ENST00000399249.6	c.2849C>T	p.Ala950Val	missense_variant	26/34	5		A2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000410 AC: 1 AN: 243916 Hom.: 0 AF XY: 0.00000753 AC XY: 1 AN XY: 132796

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000905

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000343 AC: 5 AN: 1457304 Hom.: 0 Cov.: 31 AF XY: 0.00000414 AC XY: 3 AN XY: 724758

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000225

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Alfa AF: 0.0000508 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Cardiomyopathy Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario	Mar 14, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Mar 23, 2023	This missense variant replaces alanine with valine at codon 950 of the MYBPC3 protein. Computational prediction suggests that this variant may have a deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). Splice site prediction tools are inconclusive regarding the impact of this variant on RNA splicing. To our knowledge, functional studies have not been reported for this variant. This variant has been reported in at least one individual affected with hypertrophic cardiomyopathy (PMID: 25524337, 33495597, 33782553). This variant has been identified in 1/243916 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. -

Hypertrophic cardiomyopathy Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Jun 23, 2023	An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. ClinVar contains an entry for this variant (Variation ID: 180985). This missense change has been observed in individual(s) with hypertrophic cardiomyopathy (PMID: 25524337, 33782553). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 950 of the MYBPC3 protein (p.Ala950Val). -
Uncertain significance, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	Feb 05, 2024	This missense variant replaces alanine with valine at codon 950 of the MYBPC3 protein. Computational prediction suggests that this variant may have a deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). Splice site prediction tools are inconclusive regarding the impact of this variant on RNA splicing. To our knowledge, functional studies have not been reported for this variant. This variant has been reported in at least one individual affected with hypertrophic cardiomyopathy (PMID: 25524337, 33495597, 33782553). This variant has been identified in 1/243916 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. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Feb 03, 2017

This variant is dentoed p.Ala950Val (GCA>GTA): c.2849 C>T in exon 27 of the MYBPC3 gene (NM_000256.3). The A950V variant in the MYBPC3 gene has not been reported as a disease-causing mutation or as a benign polymorphism to our knowledge. The A950V variant is a conservative amino acid substitution, which is not likely to impact secondary protein structure as these residues share similar properties. This substitution occurs at a position that is conserved across species. In silico analysis predicts A950V is probably damaging to the protein structure/function. Splice algorithms also predict A950V may affect splicing, creating a cryptic splice donor site. Mutations in nearby residues (R943Q, T957S, T958I) have been reported in association with HCM, further supporting the functional importance of this region of the protein. Furthermore, the A950V variant was not observed in approximately 6,000 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. Therefore, this variant is a strong candidate for a pathogenic mutation, however the possibility that it is a benign variant cannot be excluded. The variant is found in HCM panel(s). -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 30, 2022

The p.A950V variant (also known as c.2849C>T), located in coding exon 27 of the MYBPC3 gene, results from a C to T substitution at nucleotide position 2849. The alanine at codon 950 is replaced by valine, an amino acid with similar properties. This alteration has detected in hypertrophic cardiomyopathy (HCM) cohorts; however, clinical details were limited, and reported cases may overlap (Coppini R et al. J. Am. Coll. Cardiol., 2014 Dec;64:2589-600; Helms AS et al. Circ Genom Precis Med. 2020 10;13(5):396-405; Harper AR et al. Nat Genet. 2021 02;53(2):135-142). This variant has also been detected in exome cohorts; however, clinical detail was limited (Kars ME et al. Proc Natl Acad Sci U S A. 2021 09;118(36); Park J et al. Nat Med. 2021 01;27(1):66-72). This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.32
CardioboostCm	Benign	0.018
BayesDel_addAF	Pathogenic	0.18	D
BayesDel_noAF	Uncertain	0.020
CADD	Pathogenic	27
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.44	T;T;T
Eigen	Pathogenic	0.71
Eigen_PC	Uncertain	0.64
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.91	D;D;D
M_CAP	Pathogenic	0.67	D
MetaRNN	Pathogenic	0.93	D;D;D
MetaSVM	Benign	-0.33	T
MutationAssessor	Uncertain	2.3	M;.;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.61	T
PROVEAN	Uncertain	-3.5	D;.;D
REVEL	Pathogenic	0.74
Sift	Uncertain	0.0010	D;.;D
Sift4G	Uncertain	0.0020	D;D;D
Vest4		0.94
MVP		0.91
MPC		0.83
ClinPred		0.99	D
GERP RS		5.2
Varity_R		0.65
gMVP		0.85

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.24		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.24		Position offset: 2

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

Publications

LitVar

Other links and lift over

dbSNP: rs730880577; hg19: chr11-47356649;