14-23418223-G-C

Variant names:

• chr14-23418223-G-C
• rs727504703
• NM_000257.4:c.4156C>G

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate

The NM_000257.4(MYH7):​c.4156C>G​(p.Leu1386Val) 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L1386F) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: MYH7 NM_000257.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.79
• Publications: 1 publications found

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]

MIR208B (HGNC:33669): (microRNA 208b) microRNAs (miRNAs) are short (20-24 nt) non-coding RNAs that are involved in post-transcriptional regulation of gene expression in multicellular organisms by affecting both the stability and translation of mRNAs. miRNAs are transcribed by RNA polymerase II as part of capped and polyadenylated primary transcripts (pri-miRNAs) that can be either protein-coding or non-coding. The primary transcript is cleaved by the Drosha ribonuclease III enzyme to produce an approximately 70-nt stem-loop precursor miRNA (pre-miRNA), which is further cleaved by the cytoplasmic Dicer ribonuclease to generate the mature miRNA and antisense miRNA star (miRNA*) products. The mature miRNA is incorporated into a RNA-induced silencing complex (RISC), which recognizes target mRNAs through imperfect base pairing with the miRNA and most commonly results in translational inhibition or destabilization of the target mRNA. The RefSeq represents the predicted microRNA stem-loop. [provided by RefSeq, Sep 2009]

ACMG classification

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 17 uncertain in NM_000257.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr14-23418223-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 179201.
• PP2: Missense variant in the MYH7 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 341 curated pathogenic missense variants (we use a threshold of 10). The gene has 16 curated benign missense variants. Gene score misZ: 3.9329 (above the threshold of 3.09). Trascript score misZ: 6.7889 (above the threshold of 3.09). GenCC associations: The gene is linked to myopathy, myosin storage, autosomal recessive, MYH7-related skeletal myopathy, congenital myopathy 7A, myosin storage, autosomal dominant, Ebstein anomaly, hyaline body myopathy, left ventricular noncompaction, hypertrophic cardiomyopathy 1, dilated cardiomyopathy 1S, dilated cardiomyopathy, congenital heart disease, familial isolated dilated cardiomyopathy, myopathy, myosin storage, autosomal dominant, arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.926

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000257.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MYH7	NM_000257.4	MANE Select	c.4156C>G	p.Leu1386Val	missense	Exon 30 of 40	NP_000248.2
	MYH7	NM_001407004.1		c.4156C>G	p.Leu1386Val	missense	Exon 29 of 39	NP_001393933.1
	MIR208B	NR_030624.1		n.-160C>G		upstream_gene	N/A

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MYH7	ENST00000355349.4	TSL:1 MANE Select	c.4156C>G	p.Leu1386Val	missense	Exon 30 of 40	ENSP00000347507.3
	MYH7	ENST00000713768.1		c.4156C>G	p.Leu1386Val	missense	Exon 30 of 41	ENSP00000519070.1
	MYH7	ENST00000713769.1		c.4156C>G	p.Leu1386Val	missense	Exon 29 of 39	ENSP00000519071.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Cardiovascular phenotype Uncertain:1

Nov 18, 2022

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.L1386V variant (also known as c.4156C>G), located in coding exon 28 of the MYH7 gene, results from a C to G substitution at nucleotide position 4156. The leucine at codon 1386 is replaced by valine, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear.

Hypertrophic cardiomyopathy 1 Uncertain:1

Feb 14, 2025

3billion

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The variant is not observed in the gnomAD v4.1.0 dataset. Predicted Consequence/Location: Missense variant In silico tool predictions suggest damaging effect of the variant on gene or gene product [REVEL: 0.67 (>=0.6, sensitivity 0.68 and specificity 0.92); 3Cnet: 0.95 (>=0.6, sensitivity 0.72 and precision 0.9)]. A different missense change at the same codon (p.Leu1386Phe) has been reported to be associated with MYH7-related disorder (ClinVar ID: VCV000179201 /PMID: 27532257). However the evidence of pathogenicity is insufficient at this time. Therefore, this variant is classified as VUS according to the recommendation of ACMG/AMP guideline.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.74
CardioboostCm	Uncertain	0.69
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.050
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.84	D
Eigen	Pathogenic	0.83
Eigen_PC	Pathogenic	0.77
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D
M_CAP	Pathogenic	0.88	D
MetaRNN	Pathogenic	0.93	D
MetaSVM	Uncertain	0.54	D
MutationAssessor	Uncertain	2.8	M
PhyloP100		7.8
PrimateAI	Pathogenic	0.80	T
PROVEAN	Benign	-2.3	N
REVEL	Pathogenic	0.67
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.021	D
Polyphen		1.0	D
Vest4		0.80
MutPred		0.48		Loss of ubiquitination at K1391 (P = 0.1601)
MVP		0.97
MPC		1.6
ClinPred		0.99	D
GERP RS		4.8
Varity_R		0.63
gMVP		0.93
Mutation Taster		=3/97	disease causing

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

Other links and lift over

dbSNP: rs727504703; hg19: chr14-23887432;