NM_017534.6:c.2020C>T

Variant names:

• chr17-10535320-G-A
• rs1555571125
• NM_017534.6:c.2020C>T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_017534.6(MYH2):​c.2020C>T​(p.His674Tyr) variant causes a missense change involving the alteration of a 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 Uncertain significance (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: MYH2 NM_017534.6 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 9.98

Genes affected

MYH2 (HGNC:7572): (myosin heavy chain 2) Myosins are actin-based motor proteins that function in the generation of mechanical force in eukaryotic cells. Muscle myosins are heterohexamers composed of 2 myosin heavy chains and 2 pairs of nonidentical myosin light chains. This gene encodes a member of the class II or conventional myosin heavy chains, and functions in skeletal muscle contraction. This gene is found in a cluster of myosin heavy chain genes on chromosome 17. A mutation in this gene results in inclusion body myopathy-3. Multiple alternatively spliced variants, encoding the same protein, have been identified. [provided by RefSeq, Sep 2009]

ENSG00000272736 (HGNC:):

MYHAS (HGNC:50609): (myosin heavy chain gene cluster antisense RNA) Predicted to enable primary miRNA binding activity. Predicted to be involved in response to muscle activity and skeletal muscle fiber development. Predicted to act upstream of or within with a positive effect on gene expression. Predicted to be located in cytoplasm and nucleus. [provided by Alliance of Genome Resources, Apr 2022]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.962

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MYH2	NM_017534.6	c.2020C>T	p.His674Tyr	missense_variant	Exon 18 of 40	ENST00000245503.10	NP_060004.3
MYH2	NM_001100112.2	c.2020C>T	p.His674Tyr	missense_variant	Exon 18 of 40		NP_001093582.1
MYHAS	NR_125367.1	n.168-32217G>A		intron_variant	Intron 2 of 10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MYH2	ENST00000245503.10	c.2020C>T	p.His674Tyr	missense_variant	Exon 18 of 40	1	NM_017534.6	ENSP00000245503.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Apr 07, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2020C>T (p.H674Y) alteration is located in exon 18 (coding exon 16) of the MYH2 gene. This alteration results from a C to T substitution at nucleotide position 2020, causing the histidine (H) at amino acid position 674 to be replaced by a tyrosine (Y). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Myopathy, proximal, and ophthalmoplegia Uncertain:1

Jul 26, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces histidine, which is basic and polar, with tyrosine, which is neutral and polar, at codon 674 of the MYH2 protein (p.His674Tyr). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with MYH2-related conditions. ClinVar contains an entry for this variant (Variation ID: 534353). 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 disruptive. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.83
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.31
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.76	D;D
Eigen	Pathogenic	0.85
Eigen_PC	Pathogenic	0.82
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	.;D
M_CAP	Uncertain	0.14	D
MetaRNN	Pathogenic	0.96	D;D
MetaSVM	Uncertain	0.46	D
MutationAssessor	Uncertain	2.3	M;M
PrimateAI	Pathogenic	0.85	D
PROVEAN	Pathogenic	-4.9	D;D
REVEL	Pathogenic	0.84
Sift	Pathogenic	0.0	D;D
Sift4G	Uncertain	0.015	D;D
Polyphen		0.67	P;P
Vest4		0.90
MutPred		0.86		Loss of disorder (P = 0.0633);Loss of disorder (P = 0.0633);
MVP		0.91
MPC		1.8
ClinPred		1.0	D
GERP RS		5.0
Varity_R		0.89
gMVP		0.83

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: rs1555571125; hg19: chr17-10438637;