NM_000257.4:c.438G>C

Variant names:

• chr14-23432703-C-G
• rs397516212
• NM_000257.4:c.438G>C

Variant summary

Our verdict is Pathogenic. The variant received 19 ACMG points: 19P and 0B. PS1_Very_Strong PM1 PM2 PP2 PP3_Strong PP5_Moderate

The NM_000257.4(MYH7):​c.438G>C​(p.Lys146Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,880 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Likely pathogenic in ClinVar. Synonymous variant affecting the same amino acid position (i.e. K146K) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MYH7 NM_000257.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 3.30
• Publications: 0 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]

MYH7 Gene-Disease associations (from GenCC):

• dilated cardiomyopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• dilated cardiomyopathy 1S

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• hypertrophic cardiomyopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• hypertrophic cardiomyopathy 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: PanelApp Australia, Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• MYH7-related skeletal myopathy

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), ClinGen, Ambry Genetics
• myopathy, myosin storage, autosomal recessive

  Inheritance: AR Classification: STRONG, MODERATE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• myopathy, myosin storage, autosomal dominant

  Inheritance: AD Classification: MODERATE Submitted by: Ambry Genetics
• congenital myopathy 7A, myosin storage, autosomal dominant

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Ebstein anomaly

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• familial isolated dilated cardiomyopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• hyaline body myopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• left ventricular noncompaction

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• arrhythmogenic right ventricular cardiomyopathy

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen
• congenital heart disease

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 19 ACMG points.

• PS1: Transcript NM_000257.4 (MYH7) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar.
• PM1: In a hotspot region, there are 10 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 22 uncertain in NM_000257.4
• PM2: Very rare variant in population databases, with high coverage
• 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, 0.961
• PP5: Variant 14-23432703-C-G is Pathogenic according to our data. Variant chr14-23432703-C-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 3230910.Status of the report is criteria_provided_single_submitter, 1 stars.

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.438G>C	p.Lys146Asn	missense	Exon 5 of 40	NP_000248.2
	MYH7	NM_001407004.1		c.438G>C	p.Lys146Asn	missense	Exon 4 of 39	NP_001393933.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MYH7	ENST00000355349.4	TSL:1 MANE Select	c.438G>C	p.Lys146Asn	missense	Exon 5 of 40	ENSP00000347507.3
	MYH7	ENST00000713768.1		c.438G>C	p.Lys146Asn	missense	Exon 5 of 41	ENSP00000519070.1
	MYH7	ENST00000713769.1		c.438G>C	p.Lys146Asn	missense	Exon 4 of 39	ENSP00000519071.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461880 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 727240

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1112010

Other (OTH) AF: 0.00 AC: 0 AN: 60392

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Cardiovascular phenotype Pathogenic:1

Aug 20, 2025

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.438G>C (p.K146N) alteration is located in exon 5 (coding exon 3) of the MYH7 gene. This alteration results from a G to C substitution at nucleotide position 438, causing the lysine (K) at amino acid position 146 to be replaced by an asparagine (N). This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). This variant (and c.438G>T, which also results in p.K146N) has been detected in probands with hypertrophic cardiomyopathy (HCM), including a de novo occurrence, and has been reported to segregate with HCM in at least one family (Ingles, 2005; Walsh, 2017; Ross, 2017; Morita, 2008; Kim, 2024; Hagège, 2024). This amino acid position is highly conserved in available vertebrate species. The in silico prediction for this alteration is inconclusive. Based on the available evidence, this alteration is classified as likely pathogenic.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
CardioboostCm	Pathogenic	0.97
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	0.96	D
LIST_S2	Uncertain	0.86	D
M_CAP	Pathogenic	0.95	D
MetaRNN	Pathogenic	0.96	D
MetaSVM	Uncertain	0.30	D
MutationAssessor	Benign	0.75	N
PhyloP100		3.3
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
Mutation Taster		=18/82	disease causing

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

Other links and lift over

dbSNP: rs397516212; hg19: chr14-23901912;