14-23426852-T-G

Position:

• chr14-23426852-T-G

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2_Supporting PM1 PP3 PP1

This summary comes from the ClinGen Evidence Repository: The NM_000257.4(MYH7):c.1969A>C (p.Lys657Gln) variant in MYH7 has been reported in at least 1 individual with HCM and segregated with HCM in at least 3 affected relatives (PP1; Hill 2015 PMID:26337809; Walsh 2017 PMID:26337809; LMM pers. comm.). Due to potential overlap in the individuals reported, PS4_Supporting criteria is not met. This variant was absent from large population studies (PM2_Supporting; http://gnomad.broadinstitute.org, v2.1.1). Following the ClinGen Sequence Variant Interpretation (SVI) working group recommendation for weight adjustment of the PM2 criterion due to concerns that rarity in the general population may not meet the relative odds of pathogenicity for moderate evidence, the PM2 criterion was downgraded to PM2_Supporting. This variant lies in the head region of the protein (aa 181-937) and missense variants in this region are statistically more likely to be associated with HCM (PM1; Walsh 2017 PMID:27532257). Computational prediction tools and conservation analysis suggest that this variant may impact the protein (PP3). In summary, due to insufficient evidence, this variant meets criteria to be classified as uncertain significance for hypertrophic cardiomyopathy in an autosomal dominant manner. ACMG/AMP Criteria applied: PP1, PM2_Supporting, PM1, PP3. LINK:https://erepo.genome.network/evrepo/ui/classification/CA011527/MONDO:0005045/002

• Frequency: Genomes: not found (cov: 32)
• Consequence: MYH7 ENST00000355349.4 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 7.80

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 5 ACMG points.

• PM1: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.
• PP1: For more information check the summary or visit ClinGen Evidence Repository.
• PP3: For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MYH7	NM_000257.4	c.1969A>C	p.Lys657Gln	missense_variant	18/40	ENST00000355349.4	NP_000248.2
MYH7	NM_001407004.1	c.1969A>C	p.Lys657Gln	missense_variant	17/39		NP_001393933.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MYH7	ENST00000355349.4	c.1969A>C	p.Lys657Gln	missense_variant	18/40	1	NM_000257.4	ENSP00000347507	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hypertrophic cardiomyopathy Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Nov 29, 2022	This missense change has been observed in individual(s) with hypertrophic cardiomyopathy (PMID: 26337809, 27532257). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces lysine, which is basic and polar, with glutamine, which is neutral and polar, at codon 657 of the MYH7 protein (p.Lys657Gln). ClinVar contains an entry for this variant (Variation ID: 164351). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt MYH7 protein function. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Nov 15, 2013	The Lys657Gln variant in MYH7 has now been identified in 1 Caucasian adult with HCM and segregated with disease in 3 affected relatives. It has not been identi fied in large population studies. Lysine (Lys) at position 657 is highly conserv ed in mammals and across evolutionarily distant species and the change to glutam ine (Gln) was predicted to be pathogenic using a computational tool clinically v alidated by our laboratory. This tool's pathogenic prediction is estimated to be correct 94% of the time (Jordan 2011). In summary, this variant is likely to be pathogenic, though additional studies are required to fully establish its clini cal significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.82
CardioboostCm	Pathogenic	0.98
BayesDel_addAF	Uncertain	0.13	D
BayesDel_noAF	Uncertain	-0.050
CADD	Pathogenic	28
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.87	D
Eigen	Uncertain	0.67
Eigen_PC	Uncertain	0.61
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.89	D
M_CAP	Pathogenic	0.88	D
MetaRNN	Pathogenic	0.92	D
MetaSVM	Uncertain	0.59	D
MutationAssessor	Benign	1.5	L
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.83	D
PROVEAN	Uncertain	-3.3	D
REVEL	Pathogenic	0.73
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.0070	D
Polyphen		0.99	D
Vest4		0.72
MutPred		0.52		Loss of ubiquitination at K657 (P = 0.0224);
MVP		0.98
MPC		2.2
ClinPred		0.99	D
GERP RS		3.9
Varity_R		0.77
gMVP		0.94

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs727503264; hg19: chr14-23896061;