rs397515902

Positions:

• chr11-47342831-A-C
• chr11-47342831-A-G

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_000256.3(MYBPC3):​c.1456T>G​(p.Trp486Gly) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,198 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MYBPC3 NM_000256.3 missense, splice_region
• Scores: Splicing: ADA: 0.9230
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:6
• Conservation: PhyloP100: 8.74

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a domain Ig-like C2-type 3 (size 90) in uniprot entity MYPC3_HUMAN there are 33 pathogenic changes around while only 9 benign (79%) in NM_000256.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.982

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MYBPC3	NM_000256.3	c.1456T>G	p.Trp486Gly	missense_variant, splice_region_variant	16/35	ENST00000545968.6	NP_000247.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MYBPC3	ENST00000545968.6	c.1456T>G	p.Trp486Gly	missense_variant, splice_region_variant	16/35	5	NM_000256.3	ENSP00000442795.1
MYBPC3	ENST00000399249.6	c.1456T>G	p.Trp486Gly	missense_variant, splice_region_variant	15/34	5		ENSP00000382193.2
MYBPC3	ENST00000544791.1	n.1456T>G		splice_region_variant, non_coding_transcript_exon_variant	16/27	5		ENSP00000444259.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460198 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726248

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hypertrophic cardiomyopathy Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	Nov 20, 2023	This missense variant replaces tryptophan with glycine at codon 486 of the MYBPC3 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in at least three individuals affected with hypertrophic cardiomyopathy (PMID: 27532257, 32841044). This variant has not been identified 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 16, 2020	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 missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has been observed in individuals with clinical features of hypertrophic cardiomyopathy (PMID: 21943931, 27532257). ClinVar contains an entry for this variant (Variation ID: 42531). This variant is not present in population databases (ExAC no frequency). This sequence change replaces tryptophan with glycine at codon 486 of the MYBPC3 protein (p.Trp486Gly). The tryptophan residue is highly conserved and there is a large physicochemical difference between tryptophan and glycine. -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Jan 31, 2019

Variant classified as Uncertain Significance - Favor Pathogenic. The p.Trp486Gly variant in MYBPC3 has been reported in 2 individuals with HCM (Lakdawala 2011, Walsh 2017). This variant was absent from large population studies. Tryptophan (Trp) at position 486 is highly conserved in mammals and across evolutionarily distant species and the change to glycine (Gly) was predicted to be pathogenic using a computational tool clinically validated by our laboratory. This tool's pathogenic prediction is estimated to be correct 94% of the time (Jordan 2011). Additionally, this variant is located in the last three bases of the exon, which is part of the 5’ splice region. Computational tools do not suggest an impact to splicing, though, this information is not predictive enough to determine pathogenicity. In summary, while there is some suspicion for a pathogenic role, the clinical significance of the p.Trp486Gly variant is uncertain. ACMG/AMP Criteria applied: PM2; PP3; PS4_Supporting. -

Cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Oct 04, 2021

- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Apr 24, 2020

Reported in association with HCM (Lakdawala et al., 2011; Ito et al., 2017; Walsh et al., 2017); Reported in ClinVar as a variant of uncertain significance (ClinVar Variant ID# 42531; Landrum et al., 2016); Not observed in large population cohorts (Lek et al., 2016); In silico analysis, which includes protein predictors and evolutionary conservation, supports a deleterious effect; At the mRNA level, c.1456 T>G is located in the second-to-last nucleotide position of exon 16; in silico analysis supports that this variant does not alter splicing and mini-gene assays did not demonstrate this variant alters splicing (Ito et al., 2017); This variant is associated with the following publications: (PMID: 31006259, 21943931, 28679633, 27532257) -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 13, 2023

The p.W486G variant (also known as c.1456T>G), located in coding exon 16 of the MYBPC3 gene, results from a T to G substitution at nucleotide position 1456. The tryptophan at codon 486 is replaced by glycine, an amino acid with highly dissimilar properties. This variant has been reported in individuals with hypertrophic cardiomyopathy (HCM) (Walsh R et al. Genet Med, 2017 Feb;19:192-203; Field E et al. J Med Genet, 2022 Aug;59:768-775). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. 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	Pathogenic	0.98
CardioboostCm	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.60	D
BayesDel_noAF	Pathogenic	0.63
CADD	Pathogenic	31
DANN	Benign	0.97
DEOGEN2	Pathogenic	0.88	D;T;T
Eigen	Pathogenic	0.89
Eigen_PC	Pathogenic	0.74
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.97	D;D;D
M_CAP	Pathogenic	0.91	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.8	H;.;.
PrimateAI	Uncertain	0.78	T
PROVEAN	Pathogenic	-11	D;.;D
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D;.;D
Sift4G	Uncertain	0.0090	D;D;D
Vest4		0.98
MVP		0.99
MPC		1.1
ClinPred		0.99	D
GERP RS		4.5
Varity_R		0.97
gMVP		0.94

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.92
dbscSNV1_RF	Pathogenic	0.79
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs397515902; hg19: chr11-47364382;