rs397516212

Positions:

• chr14-23432703-C-A
• chr14-23432703-C-T

Variant summary

Our verdict is Pathogenic. Variant got 21 ACMG points: 21P and 0B. PS1 PM1 PM2 PP2 PP3_Strong PP5_Very_Strong

The NM_000257.4(MYH7):​c.438G>T​(p.Lys146Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another nucleotide change resulting in same amino acid change has been previously reported as Likely pathogenicin ClinVar. Synonymous variant affecting the same amino acid position (i.e. K146K) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MYH7 NM_000257.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 3.30

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 Pathogenic. Variant got 21 ACMG points.

• PS1: Transcript NM_000257.4 (MYH7) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar as 3230910
• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 11 uncertain in NM_000257.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, MYH7
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.961
• PP5: Variant 14-23432703-C-A is Pathogenic according to our data. Variant chr14-23432703-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 43013.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr14-23432703-C-A is described in Lovd as [Pathogenic]. Variant chr14-23432703-C-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MYH7	NM_000257.4	c.438G>T	p.Lys146Asn	missense_variant	5/40	ENST00000355349.4
MYH7	NM_001407004.1	c.438G>T	p.Lys146Asn	missense_variant	4/39

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MYH7	ENST00000355349.4	c.438G>T	p.Lys146Asn	missense_variant	5/40	1	NM_000257.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hypertrophic cardiomyopathy Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jun 13, 2019	Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). For these reasons, this variant has been classified as Pathogenic. This variant has been reported in several individuals with hypertrophic cardiomyopathy (HCM) and observed to be de novo in an individual affected with HCM (PMID: 28615295, 18403758, 27532257). ClinVar contains an entry for this variant (Variation ID: 43013). This sequence change replaces lysine with asparagine at codon 146 of the MYH7 protein (p.Lys146Asn). The lysine residue is highly conserved and there is a moderate physicochemical difference between lysine and asparagine. This variant is not present in population databases (ExAC no frequency). -
Pathogenic, no assertion criteria provided	research	Agnes Ginges Centre for Molecular Cardiology, Centenary Institute	Feb 26, 2020	This MYH7 Lys146Asn variant has been reported as a de novo mutation in a sporadic childhood cardiomyopathy case (Morita H, et al., 2008). This mutation is absent from the Genome Aggregation Database (http://gnomad.broadinstitute.org/). Here we report this variant in 3 unrelated HCM index cases (Ingles, et al., 2005; Ingles et al., 2017). In one of our families this variant segregates to multiple affected individuals (5 meiosis). In silico tools PolyPhen2, SIFT and MutationTaster predict this variant to be deleterious. Furthermore functional studies suggest that this variant disrupts the interaction of the N-terminus and lever arm of the myosin heavy chain protein and the drosophila model recapitulated a cardiomyopathy phenotype (Trujillo et al., 2017). Based on the adapted ACMG criteria (Kelly MA, et al., 2018) this variant has been shown to have a damaging affect on protein in a functional study (PS3), is rare in the general population (PM2), as been reported in a de novo case (PM6), segregates with disease (PP1_moderate), has been reported in HCM probands (PS4_supporting) and multiple in silico tools predict that this variant is deleterious (PP3), therefore we classify MYH7 Lys146Asn as 'Pathogenic'. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Mar 21, 2013	proposed classification - variant undergoing re-assessment, contact laboratory -

Cardiomyopathy Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

May 31, 2021

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
CardioboostCm	Pathogenic	0.98
BayesDel_addAF	Uncertain	0.055	T
BayesDel_noAF	Benign	-0.16
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.85	D
Eigen	Benign	0.17
Eigen_PC	Benign	0.10
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.86	D
M_CAP	Pathogenic	0.94	D
MetaRNN	Pathogenic	0.96	D
MetaSVM	Uncertain	0.30	D
MutationAssessor	Benign	0.75	N
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.86	D
PROVEAN	Uncertain	-3.1	D
REVEL	Pathogenic	0.75
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0020	D
Polyphen		0.99	D
Vest4		0.86
MutPred		0.77		Gain of catalytic residue at P151 (P = 5e-04);
MVP		0.92
MPC		2.3
ClinPred		0.99	D
GERP RS		2.7
Varity_R		0.73
gMVP		0.91

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: rs397516212; hg19: chr14-23901912;