11-47350014-C-T

Position:

• chr11-47350014-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_000256.3(MYBPC3):​c.505G>A​(p.Gly169Ser) variant causes a missense, splice region change. The variant allele was found at a frequency of 0.0000197 in 152,234 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. 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. G169R) has been classified as Uncertain significance.

• Frequency: Genomes: 𝑓 0.000020 (0 hom., cov: 33)
• Consequence: MYBPC3 NM_000256.3 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.14

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 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MYBPC3	NM_000256.3	c.505G>A	p.Gly169Ser	missense_variant, splice_region_variant	4/35	ENST00000545968.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MYBPC3	ENST00000545968.6	c.505G>A	p.Gly169Ser	missense_variant, splice_region_variant	4/35	5	NM_000256.3	P4
MYBPC3	ENST00000399249.6	c.505G>A	p.Gly169Ser	missense_variant, splice_region_variant	4/34	5		A2
MYBPC3	ENST00000544791.1	c.505G>A	p.Gly169Ser	missense_variant, splice_region_variant, NMD_transcript_variant	4/27	5

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152234 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000723

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 37

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152234 Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2 AN XY: 74374

Gnomad4 AFR AF: 0.0000723

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000189

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Nov 25, 2023

This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 169 of the MYBPC3 protein (p.Gly169Ser). This variant also falls at the last nucleotide of exon 4, which is part of the consensus splice site for this exon. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with MYBPC3-related conditions. ClinVar contains an entry for this variant (Variation ID: 264628). 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. Experimental studies have shown that this missense change affects MYBPC3 function (PMID: 34097875). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this missense change is associated with inconclusive levels of altered splicing (PMID: 34097875). 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. -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 30, 2024

The p.G169S variant (also known as c.505G>A), located in coding exon 4 of the MYBPC3 gene, results from a G to A substitution at nucleotide position 505. The amino acid change results in glycine to serine at codon 169, an amino acid with similar properties. However, this change occurs in the last base pair of coding exon 4, which makes it likely to have some effect on normal mRNA splicing. This variant has been detected in an exome sequencing biobank-derived cohort; however, clinical detail were limited (Park J et al. Nat Med. 2021 01;27(1):66-72). In a minigene assay, this variant demonstrated some incomplete aberrant splicing (Suay-Corredera C et al. J Biol Chem. 2021 07;297(1):100854). This nucleotide position is highly conserved in available vertebrate species. This amino acid position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will result in the creation or strengthening of a novel splice donor site. In addition, as a missense substitution this is predicted to be inconclusive by in silico analysis. Based on the available evidence, the clinical significance of this alteration remains unclear. -

MYBPC3-related disorder Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Nov 01, 2023

The MYBPC3 c.505G>A variant is predicted to result in the amino acid substitution p.Gly169Ser. This variant was reported as a variant of uncertain significance in a study of MYBPC3 variants, and functional studies showed that is caused a significant impact on splicing (Supplementary Materials, Suay-Corredera et al. 2021. PubMed ID: 34097875). This variant is a missense change located at the last base of an exon. This variant has not been reported in a large population database (http://gnomad.broadinstitute.org), indicating this variant is rare. Although we suspect that this variant may be pathogenic, at this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.16
CardioboostCm	Uncertain	0.28
BayesDel_addAF	Pathogenic	0.25	D
BayesDel_noAF	Uncertain	0.12
CADD	Pathogenic	36
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.70	D;T;T
Eigen	Uncertain	0.66
Eigen_PC	Uncertain	0.54
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.97	D;D;D
M_CAP	Pathogenic	0.47	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Uncertain	0.55	D
MutationAssessor	Uncertain	2.6	M;.;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.64	T
PROVEAN	Pathogenic	-5.0	D;D;D
REVEL	Pathogenic	0.82
Sift	Uncertain	0.0030	D;D;D
Sift4G	Uncertain	0.041	D;D;D
Polyphen		1.0	D;.;.
Vest4		0.81
MutPred		0.84		Gain of glycosylation at G169 (P = 0.0365);Gain of glycosylation at G169 (P = 0.0365);Gain of glycosylation at G169 (P = 0.0365);
MVP		0.93
MPC		0.83
ClinPred		1.0	D
GERP RS		3.6
Varity_R		0.53
gMVP		0.66

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.97
SpliceAI score (max)		0.88		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.88		Position offset: 4

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

Publications

LitVar

Other links and lift over

dbSNP: rs886039212; hg19: chr11-47371565;