NM_000256.3:c.821+1G>C

Variant names:

• chr11-47347856-C-G
• rs397516073
• NM_000256.3:c.821+1G>C

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000256.3(MYBPC3):​c.821+1G>C variant causes a splice donor, intron change. The variant was absent in control chromosomes in GnomAD project. 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 Pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: MYBPC3 NM_000256.3 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 6.19

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 Pathogenic. Variant got 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-47347856-C-G is Pathogenic according to our data. Variant chr11-47347856-C-G is described in ClinVar as [Pathogenic]. Clinvar id is 178946.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-47347856-C-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MYBPC3	NM_000256.3	c.821+1G>C		splice_donor_variant, intron_variant	Intron 7 of 34	ENST00000545968.6	NP_000247.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MYBPC3	ENST00000545968.6	c.821+1G>C		splice_donor_variant, intron_variant	Intron 7 of 34	5	NM_000256.3	ENSP00000442795.1
MYBPC3	ENST00000399249.6	c.821+1G>C		splice_donor_variant, intron_variant	Intron 7 of 33	5		ENSP00000382193.2
MYBPC3	ENST00000544791.1	n.821+1G>C		splice_donor_variant, intron_variant	Intron 7 of 26	5		ENSP00000444259.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1412706 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 698110

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hypertrophic cardiomyopathy Pathogenic:2

May 20, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects a donor splice site in intron 7 of the MYBPC3 gene. RNA analysis indicates that disruption of this splice site induces altered splicing and may result in an absent or disrupted protein product. This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individuals with hypertrophic cardiomyopathy (PMID: 9562578, 11499718, 11499719, 25611685, 27532257). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 178946). Studies have shown that disruption of this splice site results in skipping of exon 7 or exons 7 and 8 and introduces a premature termination codon (PMID: 11499719). The resulting mRNA is expected to undergo nonsense-mediated decay. For these reasons, this variant has been classified as Pathogenic. -

Apr 21, 2013

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The 821+1G>C variant in MYBPC3 has not been reported in individuals with cardiom yopathy and data from large population studies is insufficient to assess the fre quency of this variant. This variant occurs in the invariant region (+/- 1,2) of the splice consensus sequence and is predicted to cause altered splicing leadin g to an abnormal or absent protein. Splicing and other truncating variants in MY BPC3 are established as pathogenic for HCM. In addition, other variants impactin g this splice site have been reported in individuals with HCM (821+1G>A, 821+2T> C, 821+5G>A; Carrier 1997, Niimura 1998, Flavigny 1999, Maron 2001, Flavigny 200 3, Richard 2003, Van Driest 2004, LMM unpublished data). In summary, this varian t meets our criteria to be classified as pathogenic (http://pcpgm.partners.org/L MM) based upon the predicted impact of the variant. -

Cardiovascular phenotype Pathogenic:1

Nov 06, 2020

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.821+1G>C intronic pathogenic mutation results from a G to C substitution one nucleotide after coding exon 7 of the MYBPC3 gene. This variant has been reported in a hypertrophic cardiomyopathy (HCM) genetic testing cohort; however, clinical details were limited (Alfares AA et al. Genet Med, 2015 Nov;17:880-8; Walsh R et al. Genet Med, 2017 02;19:192-203). Another alteration impacting the same donor site (c.821+1G>A) has been described in multiple families with HCM and demonstrated segregation with disease; furthermore, mRNA analysis showed exon skipping resulting in abnormal transcripts (Niimura H et al. N Engl J Med. 1998 Apr;338:1248-57; Erdmann J et al. J Am Coll Cardiol. 2001 Aug;38:322-30). In addition to the clinical data presented in the literature, alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. As such, this alteration is classified as a disease-causing mutation. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.31
CADD	Pathogenic	32
DANN	Uncertain	0.99
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.99	D
GERP RS		5.5

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.92
SpliceAI score (max)		0.87		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.87		Position offset: 1

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

Publications

LitVar

Other links and lift over

dbSNP: rs397516073; hg19: chr11-47369407;