rs876661375

chr14-23431420-G-Achr14-23431420-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP2

The NM_000257.4(MYH7):c.794C>T(p.Thr265Ile) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T265S) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MYH7 NM_000257.4 missense, splice_region
• Scores: Splicing: ADA: 0.6275
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.61

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: In a hotspot region, there are 5 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

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MYH7	NM_000257.4	c.794C>T	p.Thr265Ile	missense_variant, splice_region_variant	9/40	ENST00000355349.4
MYH7	NM_001407004.1	c.794C>T	p.Thr265Ile	missense_variant, splice_region_variant	8/39

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MYH7	ENST00000355349.4	c.794C>T	p.Thr265Ile	missense_variant, splice_region_variant	9/40	1	NM_000257.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Dec 24, 2018

Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. 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. This variant is found within a region of MYH7 between codons 181 and 937 that contains the majority of the myosin head domain. Missense variants in this region have been shown to be significantly overrepresented in individuals with hypertrophic cardiomyopathy (PMID: 27532257). This variant has not been reported in the literature in individuals with MYH7-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces threonine with isoleucine at codon 265 of the MYH7 protein (p.Thr265Ile). The threonine residue is highly conserved and there is a moderate physicochemical difference between threonine and isoleucine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.49
CardioboostCm	Pathogenic	0.93
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.22
Cadd	Pathogenic	27
Dann	Uncertain	0.98
DEOGEN2	Pathogenic	0.89	D
Eigen	Benign	-0.12
Eigen_PC	Benign	-0.034
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.80	T
M_CAP	Pathogenic	0.78	D
MetaRNN	Uncertain	0.70	D
MetaSVM	Uncertain	0.094	D
MutationAssessor	Uncertain	2.9	M
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.86	D
PROVEAN	Uncertain	-2.6	D
REVEL	Uncertain	0.63
Sift	Benign	0.26	T
Sift4G	Benign	0.14	T
Polyphen		0.0030	B
Vest4		0.42
MutPred		0.64		Gain of catalytic residue at L268 (P = 0.0048);
MVP		0.95
MPC		1.5
ClinPred		0.70	D
GERP RS		3.5
Varity_R		0.62
gMVP		0.91

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.63
dbscSNV1_RF	Benign	0.46
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: rs876661375; hg19: chr14-23900629;