NM_000256.3:c.3G>A

Variant names:

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1PS1_ModeratePM2

The NM_000256.3(MYBPC3):c.3G>A(p.Met1?) variant causes a start lost change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000188 in 1,595,446 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 Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

MYBPC3
NM_000256.3 start_lost

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1U:3

Conservation

PhyloP100: 1.83

Variant links:

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 12 ACMG points.

PVS1

Start lost variant, next in-frame start position is after 25 pathogenic variants. Next in-frame start position is after 306 CDS bases. Genomic position: 47350602. Lost 0.080 part of the original CDS.

PS1

Another start lost variant in NM_000256.3 (MYBPC3) was described as [Likely_pathogenic] in Lovd

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MYBPC3	NM_000256.3 link	c.3G>A	p.Met1?	start_lost	Exon 1 of 35	ENST00000545968.6	NP_000247.2	Q14896-1A5YM48

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
MYBPC3	ENST00000545968.6 link	c.3G>A	p.Met1?	start_lost	Exon 1 of 35	5	NM_000256.3	ENSP00000442795.1	Q14896-1
MYBPC3	ENST00000399249.6 link	c.3G>A	p.Met1?	start_lost	Exon 1 of 34	5		ENSP00000382193.2	A8MXZ9
MYBPC3	ENST00000544791.1 link	n.3G>A		non_coding_transcript_exon_variant	Exon 1 of 27	5		ENSP00000444259.1	F5GZR4

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152112

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000193

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

GnomAD3 exomes

AF:

0.00000433

AC:

AN:

231038

Hom.:

AF XY:

0.00000793

AC XY:

AN XY:

126104

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000653

Gnomad SAS 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:

0.00000139

AC:

AN:

1443334

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

717890

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000537

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152112

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74316

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000193

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.0000302

ExAC

AF:

0.00000827

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:3

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Hypertrophic cardiomyopathy

Uncertain:2

Aug 27, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects the initiator methionine of the MYBPC3 mRNA. The next in-frame methionine is located at codon 103. This variant is present in population databases (rs397516045, ExAC 0.01%). Disruption of the initiator codon has been observed in individual(s) with hypertrophic cardiomyopathy (PMID: 25611685, 27532257, 29524613). Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. 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. -

Jun 15, 2023

All of Us Research Program, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant results in the loss of the translation initiator methionine at codon 1 of the MYBPC3 protein. This variant is expected to disrupt the expression of the full-length MYBPC3 protein. The next in-frame methionine occurs at codon 103 in the Ig-like domain C0. To our knowledge, functional studies have not been reported for this variant. This variant has been reported in compound heterozygous state with a truncation variant (p. Ile292PhefsTer8) in two siblings affected with hypertrophic cardiomyopathy, and in heterozygous state in their unaffected mother (PMID: 29524613). Different single nucleotide substitutions (c.3G>C, c.1A>T) causing the same initiator codon loss have been reported in two probands affected with hypertrophic cardiomyopathy (PMID: 25611685, 27532257). This variant has been identified in 2/262394 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

Pathogenic:1

Mar 02, 2023

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Observed with a frameshift variant on the opposite allele (in trans) in twin siblings with hypertrophic cardiomyopathy in published literature; the c.3G>A variant was heterozygous in the asymptomatic father with normal echocardiogram (Zhou et al., 2018); Observed in a cohort of patients with sporadic dilated cardiomyopathy, although patient specific clinical information and familial segregation information were not provided (Xiao et al., 2021); Initiation codon variant 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: 28679633, 29524613, 33996946) -

Cardiomyopathy

Uncertain:1

Jun 06, 2023

Color Diagnostics, LLC DBA Color Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant results in the loss of the translation initiator methionine at codon 1 of the MYBPC3 protein. This variant is expected to disrupt the expression of the full-length MYBPC3 protein. The next in-frame methionine occurs at codon 103 in the Ig-like domain C0. To our knowledge, functional studies have not been reported for this variant. This variant has been reported in compound heterozygous state with a truncation variant (p. Ile292PhefsTer8) in two siblings affected with hypertrophic cardiomyopathy, and in heterozygous state in their unaffected parent (PMID: 29524613). It has also been reported in an individual affected with dilated cardiomyopathy (PMID: 33996946). Different single nucleotide substitutions (c.3G>C, c.1A>T) causing the same initiator codon loss have been reported in individuals affected with hypertrophic cardiomyopathy (PMID: 25611685, 27532257, 30297972; communication with an external laboratory; ClinVar SCV003852942.1, SCV001504154.3). This variant has been identified in 2/262394 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

Uncertain

0.15

BayesDel_noAF

Pathogenic

0.16

CADD

Uncertain

DANN

Uncertain

1.0

DEOGEN2

Benign

0.23

T;T;T

Eigen

Uncertain

0.53

Eigen_PC

Uncertain

0.53

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Uncertain

0.90

D;D;D

M_CAP

Pathogenic

0.55

MetaRNN

Pathogenic

0.98

D;D;D

MetaSVM

Benign

-0.35

PROVEAN

Benign

-1.5

N;N;N

REVEL

Uncertain

0.36

Sift

Pathogenic

0.0

D;D;D

Sift4G

Pathogenic

0.0

D;D;D

Polyphen

0.85

P;.;.

Vest4

0.94

MutPred

0.89

Gain of catalytic residue at M1 (P = 0.0885);Gain of catalytic residue at M1 (P = 0.0885);Gain of catalytic residue at M1 (P = 0.0885);

MVP

0.83

ClinPred

0.98

GERP RS

4.5

Varity_R

0.95

gMVP

0.23

Splicing

Name

Calibrated prediction

Score

Prediction

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over