rs727504362

Positions:

• chr14-23431619-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM2 PM5 PP2 PP3_Strong

The NM_000257.4(MYH7):​c.698C>T​(p.Ala233Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,894 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A233S) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MYH7 NM_000257.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 9.78

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 Likely_pathogenic. Variant got 9 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr14-23431620-C-A is described in Lovd as [Pathogenic].
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), MYH7. . Gene score misZ 3.9329 (greater than the threshold 3.09). Trascript score misZ 6.7889 (greater than threshold 3.09). GenCC has associacion of gene with hyaline body myopathy, MYH7-related skeletal myopathy, dilated cardiomyopathy 1S, congenital myopathy 7A, myosin storage, autosomal dominant, dilated cardiomyopathy, left ventricular noncompaction, myopathy, myosin storage, autosomal dominant, hypertrophic cardiomyopathy, congenital heart disease, Ebstein anomaly, arrhythmogenic right ventricular cardiomyopathy, myopathy, myosin storage, autosomal recessive, hypertrophic cardiomyopathy 1, familial isolated dilated cardiomyopathy.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.967

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MYH7	NM_000257.4	c.698C>T	p.Ala233Val	missense_variant	8/40	ENST00000355349.4	NP_000248.2
MYH7	NM_001407004.1	c.698C>T	p.Ala233Val	missense_variant	7/39		NP_001393933.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MYH7	ENST00000355349.4	c.698C>T	p.Ala233Val	missense_variant	8/40	1	NM_000257.4	ENSP00000347507	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461894 Hom.: 0 Cov.: 34 AF XY: 0.00000138 AC XY: 1 AN XY: 727248

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, no assertion criteria provided	provider interpretation	Stanford Center for Inherited Cardiovascular Disease, Stanford University	Oct 11, 2017	Found in a pediatric patient with LVNC who had a Comprehensive Cardiomyopathy Panel with the GeneDx laboratory. The test included sequencing of 76 genes and additional deletion/duplication analysis of 60 of those genes (nuclear genes) associated with various forms of cardiomyopathy: ABCC9 , ACTC (ACTC1), ACTN2, ANKRD1, BAG3 , BRAF, CAV3, CRYAB , CSRP3, DES, DMD, DSC2, DSG2, DSP, DTNA, EMD, FKTN, GATAD1, GLA, HRAS, ILK, JPH2, JUP, KRAS, LAMA4, LAMP2, LDB3 (ZASP), LMNA, MAP2K1, MAP2K2, MTND1, MTND5, MTND6, MTTD, MTTG, MTTH, MTTI, MTTK, MTTL1, MTTL2, MTTM, MTTQ, MTTS1, MTTS2, MYBPC3, MYH7, MYL2, MYL3, MYLK2, MYOZ2, MYPN, NEBL , NEXN, NRAS, PDLIM3, PKP2, PLN, PRKAG2, PTPN11, RAF1, RBM20, RYR2, SCN5A, SGCD, SOS1, TAZ, TCAP, TMEM43, TMPO, TNNC1, TNNI3, TNNT2, TPM1, TTN, TTR, VCL. Results show that 2 variants were detected: • p.Glu561_Glu562del (c.1677_1682delGGAGGA) in the NEXN gene - which we consider likely to be benign because it is 10x more frequent in patients with African ancestry such as this patient • p.Ala233Val (c.698C>T) in the MYH7 gene p.Ala233Val (c.698C>T) in exon 8 of the MYH7 gene Chromosome location 14:23900828 G / A Based on the data reviewed below we consider this to be a Variant of Uncertain Significance, but still consider it a good candidate to be disease-causing. More data is required to understand its clinical significance. This variant has not been reported in the literature in association with disease, to the best of our knowledge. Girolami et al. (2006) reported a different variant at the same residue, Ala233Ser, in an Italian patient with hypertrophic cardiomyopathy. This is a conservative amino acid change, resulting in the replacement of a nonpolar Alanine with a nonpolar Valine. Alanine at this location is absolutely conserved across ~100 vertebrate species for which we have data. The adjacent residues are also highly conserved. Missense variants at nearby residues (+/- 10 amino acids), including a different missense variant at the same residue (Ala233Ser), have been reported in ClinVar as Likely Pathogenic or Pathogenic: Arg243His, Asp239Asn, Arg237Trp, Ala233Ser, Ala226Val, Ala226Thr. This supports the functional importance of this region of the protein. The variant is in the head of myosin, which is enriched for pathogenic variation. Specifically, it is in the ATP-binding domain. In silico prediction models are not in agreement regarding this variant. Analysis with Mutation Taster considers it “disease causing” while PolyPhen-2 predicts that it is "benign." There is no variation at this residue reported in the gnomAD database, which includes variant calls on ~140,000 individuals of European, African, Latino, South Asian, Ashkenazi, and East Asian descent. There is good coverage at this site. The phenotype of those individuals is not publicly available. The dataset is comprised of multiple cohorts, some of which were recruited from the general population, others were enriched for common cardiovascular disease. The curators made an effort to exclude individuals with severe pediatric diseases. -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Oct 14, 2015	Although the A233V variant has not been reported as a pathogenic variant or a benign variant, to our knowledge, it has previously been identified in one other individual who underwent genetic testing for cardiomyopathy . This variant was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. Missense variants in nearby residues (A223T, L227V, N232S, T235N, V236I, D239N, R243C, R243H) including a different missense variant at the same residue (A233S) have been reported in HGMD in association with cardiomyopathy (Stenson et al., 2014), supporting the functional importance of this residue and region of the protein. This substitution occurs at a position that is conserved across species. However, the A233V variant is a conservative amino acid substitution, which is not likely to impact secondary protein structure as these residues share similar properties. Furthermore, in silico analysis is inconsistent in its predictions as to whether or not the variant is damaging to the protein structure/function. -

not specified Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Jan 17, 2014

proposed classification - variant undergoing re-assessment, contact laboratory -

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 16, 2021

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"). 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). 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. ClinVar contains an entry for this variant (Variation ID: 177858). This variant has not been reported in the literature in individuals affected with MYH7-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces alanine with valine at codon 233 of the MYH7 protein (p.Ala233Val). The alanine residue is highly conserved and there is a small physicochemical difference between alanine and valine. -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Apr 21, 2021

The p.A233V variant (also known as c.698C>T), located in coding exon 6 of the MYH7 gene, results from a C to T substitution at nucleotide position 698. The alanine at codon 233 is replaced by valine, an amino acid with similar properties. This alteration is located in the myosin head domain, which contains a statistically significant clustering of pathogenic missense variants (Homburger JR et al. Proc Natl Acad Sci U S A, 2016 06;113:6701-6; Walsh R et al. Genet Med, 2017 02;19:192-203; Ambry internal data). Another alteration at the same amino acid position, p.A233S, has been reported in individuals with hypertrophic cardiomyopathy (HCM) (Homburger JR et al. Proc Natl Acad Sci U S A, 2016 06;113:6701-6).This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
CardioboostCm	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.95	D
Eigen	Uncertain	0.42
Eigen_PC	Uncertain	0.40
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.99	D
MetaRNN	Pathogenic	0.97	D
MetaSVM	Pathogenic	1.2	D
MutationAssessor	Pathogenic	3.7	H
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.82	D
PROVEAN	Uncertain	-3.2	D
REVEL	Pathogenic	0.93
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.013	D
Polyphen		0.15	B
Vest4		0.97
MutPred		0.79		Gain of catalytic residue at K234 (P = 0);
MVP		0.99
MPC		2.1
ClinPred		0.99	D
GERP RS		3.5
Varity_R		0.79
gMVP		0.99

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: rs727504362; hg19: chr14-23900828;