rs397516041

chr11-47332089-C-T

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.3797G>A(p.Cys1266Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. C1266R) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: MYBPC3 NM_000256.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:7
• Conservation: PhyloP100: 7.56

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 hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 13 uncertain in NM_000256.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.944

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MYBPC3	NM_000256.3	c.3797G>A	p.Cys1266Tyr	missense_variant	33/35	ENST00000545968.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MYBPC3	ENST00000545968.6	c.3797G>A	p.Cys1266Tyr	missense_variant	33/35	5	NM_000256.3	P4
MYBPC3	ENST00000399249.6	c.3797G>A	p.Cys1266Tyr	missense_variant	32/34	5		A2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:7

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Jul 23, 2020	Reported in ClinVar as a variant of uncertain significance (ClinVar Variant ID# 42743; Landrum et al., 2016); Not observed in large population cohorts (Lek et al., 2016); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 27532257, 22267749, 31006259) -
Uncertain significance, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Sep 18, 2023	The p.Cys1266Tyr variant in MYBPC3 has been reported in at least 2 individuals with hypertrophic cardiomyopathy (HCM) and segregated with disease in 1 affected relative. (Page 2012 PMID: 22267749, Walsh 2017 PMID: 27532257, Thompson 2021 PMID: 33782553, LMM internal data). It was also identified in 1 individual with a clinical diagnosis of cardiomyopathy with no additional details provided (Pottinger 2020 PMID: 32009526). This variant has been reported by other clinical laboratories in ClinVar (Variation ID 42743) and was absent from large population studies (gnomAD v.3.1.2). Computational prediction tools and conservation analyses do not provide strong support for or against an impact to the protein. In summary, the clinical significance of this variant is uncertain. ACMG/AMP Criteria applied: PM2_Supporting, PS4_Supporting. -

Hypertrophic cardiomyopathy Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	May 31, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Nov 23, 2022	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. 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. ClinVar contains an entry for this variant (Variation ID: 42743). This missense change has been observed in individual(s) with hypertrophic cardiomyopathy (PMID: 22267749, 27532257, 33782553). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces cysteine, which is neutral and slightly polar, with tyrosine, which is neutral and polar, at codon 1266 of the MYBPC3 protein (p.Cys1266Tyr). -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Dec 05, 2022

Variant summary: MYBPC3 c.3797G>A (p.Cys1266Tyr) results in a non-conservative amino acid change located in the Immunoglobulin-like domain (IPR007110) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 248458 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.3797G>A has been reported in the literature in individuals affected with Hypertrophic Cardiomyopathy (examples: Page_2012, Walsh_2017). These data however, do not allow any conclusion about variant significance. Furthermore, at-least two subsequent reports on this variant have reported its significance as a VUS (Pottinger_2020). The variant was also identified within three members of a family referred for testing on an 8-gene HCM panel at our laboratory. However, no additional information (clinical or family history) is available. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and all classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Hypertrophic cardiomyopathy 4;C3715165:Left ventricular noncompaction 10 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Sep 23, 2021

- -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 23, 2023

The p.C1266Y variant (also known as c.3797G>A), located in coding exon 33 of the MYBPC3 gene, results from a G to A substitution at nucleotide position 3797. The cysteine at codon 1266 is replaced by tyrosine, an amino acid with highly dissimilar properties. This alteration has been reported in hypertrophic cardiomyopathy (HCM) cohorts; however, clinical details were limited (Page SP et al. Circ Cardiovasc Genet, 2012 Apr;5:156-66; Walsh R et al. Genet. Med., 2017 02;19:192-203; Norrish G et al. Circulation, 2019 Jul;140:184-192). 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	0.91
CardioboostCm	Pathogenic	0.91
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
Cadd	Pathogenic	34
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.76	D;T;T
Eigen	Pathogenic	0.76
Eigen_PC	Pathogenic	0.77
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	D;D;D
M_CAP	Pathogenic	0.62	D
MetaRNN	Pathogenic	0.94	D;D;D
MetaSVM	Uncertain	-0.14	T
MutationAssessor	Benign	1.8	L;.;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.72	T
PROVEAN	Pathogenic	-9.6	D;.;D
REVEL	Pathogenic	0.72
Sift	Pathogenic	0.0	D;.;D
Sift4G	Pathogenic	0.0	D;D;D
Vest4		0.97
MVP		0.92
MPC		1.1
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.98
gMVP		0.98

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.50		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.50		Position offset: 7

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

Publications

LitVar

Other links and lift over

dbSNP: rs397516041; hg19: chr11-47353640;