rs397516066

Positions:

• chr11-47349769-C-G
• chr11-47349769-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_000256.3(MYBPC3):​c.654+5G>C variant causes a splice donor 5th base, intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: MYBPC3 NM_000256.3 splice_donor_5th_base, intron
• Scores: Splicing: ADA: 0.9995
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 1.06

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 3 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. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MYBPC3	NM_000256.3	c.654+5G>C		splice_donor_5th_base_variant, intron_variant		ENST00000545968.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MYBPC3	ENST00000545968.6	c.654+5G>C		splice_donor_5th_base_variant, intron_variant		5	NM_000256.3	P4
MYBPC3	ENST00000399249.6	c.654+5G>C		splice_donor_5th_base_variant, intron_variant		5		A2
MYBPC3	ENST00000544791.1	c.654+5G>C		splice_donor_5th_base_variant, intron_variant, NMD_transcript_variant		5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 28, 2023

This sequence change falls in intron 5 of the MYBPC3 gene. It does not directly change the encoded amino acid sequence of the MYBPC3 protein. RNA analysis indicates that this variant induces altered splicing and likely results in the loss of 16 amino acid residue(s), but is expected to preserve the integrity of the reading-frame. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with hypertrophic cardiomyopathy (PMID: 30645170). ClinVar contains an entry for this variant (Variation ID: 263572). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant results in the activation of a cryptic splice site in exon 5 (PMID: 30645170). 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

Oct 17, 2023

The c.654+5G>C intronic variant results from a G to C substitution 5 nucleotides after coding exon 5 in the MYBPC3 gene. This alteration has been reported in an individual with hypertrophic cardiomyopathy, and RNA studies showed this alteration may impact protein function (Singer ES et al. Circ Genom Precis Med, 2019 01;12:e002368). This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis 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
BayesDel_noAF	Benign	-0.44
CADD	Benign	21
DANN	Benign	0.70

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.92
SpliceAI score (max)		0.14		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: rs397516066; hg19: chr11-47371320;