rs397516224

Variant names:

• chr14-23432683-TG-T
• rs397516224
• NM_000257.4:c.457delC

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

This summary comes from the ClinGen Evidence Repository: The c.457del (p.His153Thrfs*14) variant in MYH7 has been identified in a 6 month old with DCM that also had a second variant in MYH7 (LMM pers comm) as well as 2 cases in the literature without clinical information (Ceyhan-Birsoy 2019 PMID:30609409; Zimmerman 2010 PMID:20474083), which is insufficient to apply PS4_Supporting. This variant has been identified in 0.000879% (1/113760) of European (Non-Finnish) chromosomes in gnomAD v2.1.1 (PM2; https://gnomad.broadinstitute.org). This variant is predicted to cause a frameshift leading to a truncated or absent protein and the contribution of LOF variants in MYH7 to autosomal dominant inherited cardiomyopathy is incompletely understood. In summary, due to a lack of evidence, this variant is classified as uncertain significance for cardiomyopathy in an autosomal dominant manner. MYH7-specific ACMG/AMP criteria applied (Kelly 2018 PMID:29300372): PM2. LINK:https://erepo.genome.network/evrepo/ui/classification/CA015125/MONDO:0004994/002

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: MYH7 NM_000257.4 frameshift
• Clinical Significance: Uncertain significance reviewed by expert panel P:1 U:2
• Conservation: PhyloP100: 9.75

Genes affected

MYH7 (HGNC:7577): (myosin heavy chain 7) Muscle myosin is a hexameric protein containing 2 heavy chain subunits, 2 alkali light chain subunits, and 2 regulatory light chain subunits. This gene encodes the beta (or slow) heavy chain subunit of cardiac myosin. It is expressed predominantly in normal human ventricle. It is also expressed in skeletal muscle tissues rich in slow-twitch type I muscle fibers. Changes in the relative abundance of this protein and the alpha (or fast) heavy subunit of cardiac myosin correlate with the contractile velocity of cardiac muscle. Its expression is also altered during thyroid hormone depletion and hemodynamic overloading. Mutations in this gene are associated with familial hypertrophic cardiomyopathy, myosin storage myopathy, dilated cardiomyopathy, and Laing distal myopathy. [provided by RefSeq, May 2022]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MYH7	NM_000257.4	c.457delC	p.His153ThrfsTer14	frameshift_variant	Exon 5 of 40	ENST00000355349.4	NP_000248.2
MYH7	NM_001407004.1	c.457delC	p.His153ThrfsTer14	frameshift_variant	Exon 4 of 39		NP_001393933.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MYH7	ENST00000355349.4	c.457delC	p.His153ThrfsTer14	frameshift_variant	Exon 5 of 40	1	NM_000257.4	ENSP00000347507.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251486 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135914

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461848 Hom.: 0 Cov.: 33 AF XY: 0.00000275 AC XY: 2 AN XY: 727220

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: 8.99e-7

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1 Uncertain:2

Revision: reviewed by expert panel

Submissions by phenotype

Primary dilated cardiomyopathy Pathogenic:1

Apr 06, 2016

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.His153ThrfsX14 variant in MYH7 has been identified in one individual with cardiomyopathy (in trans with another MYH7 variant) but has not been observed in large population studies. This variant is predicted to cause a frameshift, whic h alters the protein?s amino acid sequence beginning at position 153 and leads t o a premature termination codon 14 amino acids downstream. This alteration is th en predicted to lead to a truncated or absent protein. Although heterozygous los s-of-function (LOF) variants in MYH7, such as this variant, are not believed to be pathogenic for the dominant condition more classically associated to MYH7, wh en a LOF variant is found in trans with another variant affecting function, a mo re severe and early-onset cardiomyopathy presentation can occur (LMM unpublished data). It should be noted that loss of function variants in the MYH7 gene are very rare and therefore an understanding of their potential impact is not well s tudied. In summary, this variant leads to a predicted loss-of-function of the pr otein and, although additional studies are required to fully establish its clini cal significance, it is likely pathogenic for a recessive presentation. -

Cardiomyopathy Uncertain:1

Aug 25, 2021

ClinGen Cardiomyopathy Variant Curation Expert Panel

Significance: Uncertain significance

Review Status: reviewed by expert panel

Collection Method: curation

The c.457del (p.His153Thrfs*14) variant in MYH7 has been identified in a 6 month old with DCM that also had a second variant in MYH7 (LMM pers comm) as well as 2 cases in the literature without clinical information (Ceyhan-Birsoy 2019 PMID: 30609409; Zimmerman 2010 PMID: 20474083), which is insufficient to apply PS4_Supporting. This variant has been identified in 0.000879% (1/113760) of European (Non-Finnish) chromosomes in gnomAD v2.1.1 (PM2; https://gnomad.broadinstitute.org). This variant is predicted to cause a frameshift leading to a truncated or absent protein and the contribution of LOF variants in MYH7 to autosomal dominant inherited cardiomyopathy is incompletely understood. In summary, due to a lack of evidence, this variant is classified as uncertain significance for cardiomyopathy in an autosomal dominant manner. MYH7-specific ACMG/AMP criteria applied (Kelly 2018 PMID:29300372): PM2. -

Hypertrophic cardiomyopathy Uncertain:1

Jul 19, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. ClinVar contains an entry for this variant (Variation ID: 43028). This premature translational stop signal has been observed in individual(s) with dilated cardiomyopathy (PMID: 20474083). This variant is present in population databases (rs397516224, gnomAD 0.0009%). This sequence change creates a premature translational stop signal (p.His153Thrfs*14) in the MYH7 gene. It is expected to result in an absent or disrupted protein product. However, the current clinical and genetic evidence is not sufficient to establish whether loss-of-function variants in MYH7 cause disease. -

Computational scores

Source: dbNSFP v4.3

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

Other links and lift over

dbSNP: rs397516224; hg19: chr14-23901892;