rs373475989

Variant names:

• chr12-110914231-T-C
• rs373475989
• NM_000432.4:c.229A>G

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 3P and 1B. PM1 PP2 BP4

The NM_000432.4(MYL2):​c.229A>G​(p.Ile77Val) variant causes a missense change. The variant allele was found at a frequency of 0.00000372 in 1,613,954 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign 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. I77T) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: MYL2 NM_000432.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 4.80
• Publications: 0 publications found

Genes affected

MYL2 (HGNC:7583): (myosin light chain 2) This gene encodes a major sarcomeric protein in mammalian striated muscle. The encoded protein plays a role in embryonic heart muscle structure and function, while phosphorylation of the encoded protein is involved in cardiac myosin cycling kinetics, torsion and function in adults. Mutations in this gene are associated with hypertrophic cardiomyopathy 10 and infant-onset myopathy. [provided by RefSeq, May 2022]

MYL2 Gene-Disease associations (from GenCC):

• hypertrophic cardiomyopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• hypertrophic cardiomyopathy 10

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: ClinGen, G2P, PanelApp Australia, Labcorp Genetics (formerly Invitae)
• myopathy, myofibrillar, 12, infantile-onset, with cardiomyopathy

  Inheritance: AR Classification: MODERATE Submitted by: Ambry Genetics
• congenital fiber-type disproportion myopathy

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

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen
• arrhythmogenic right ventricular cardiomyopathy

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PM1: In a chain Myosin regulatory light chain 2, ventricular/cardiac muscle isoform (size 164) in uniprot entity MLRV_HUMAN there are 22 pathogenic changes around while only 6 benign (79%) in NM_000432.4
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 11 curated pathogenic missense variants (we use a threshold of 10). The gene has 2 curated benign missense variants. Gene score misZ: 0.39564 (below the threshold of 3.09). Trascript score misZ: 1.1124 (below the threshold of 3.09). GenCC associations: The gene is linked to hypertrophic cardiomyopathy 10, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy, myopathy, myofibrillar, 12, infantile-onset, with cardiomyopathy, congenital fiber-type disproportion myopathy.
• BP4: Computational evidence support a benign effect (MetaRNN=0.2706479).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000432.4. 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
	MYL2	NM_000432.4	MANE Select	c.229A>G	p.Ile77Val	missense	Exon 4 of 7	NP_000423.2
	MYL2	NM_001406745.1		c.187A>G	p.Ile63Val	missense	Exon 3 of 6	NP_001393674.1
	MYL2	NM_001406916.1		c.172A>G	p.Ile58Val	missense	Exon 4 of 7	NP_001393845.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MYL2	ENST00000228841.15	TSL:1 MANE Select	c.229A>G	p.Ile77Val	missense	Exon 4 of 7	ENSP00000228841.8
	MYL2	ENST00000713800.1		c.229A>G	p.Ile77Val	missense	Exon 5 of 8	ENSP00000519106.1
	MYL2	ENST00000713803.1		c.229A>G	p.Ile77Val	missense	Exon 5 of 8	ENSP00000519109.1

Frequencies

GnomAD3 genomes AF: 0.0000132 AC: 2 AN: 152076 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000483

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461878 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 727238

African (AFR) AF: 0.00 AC: 0 AN: 33480

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: 0.0000116 AC: 1 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1112000

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome AF: 0.0000132 AC: 2 AN: 152076 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74284

African (AFR) AF: 0.0000483 AC: 2 AN: 41398

American (AMR) AF: 0.00 AC: 0 AN: 15274

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5196

South Asian (SAS) AF: 0.00 AC: 0 AN: 4810

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10612

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68000

Other (OTH) AF: 0.00 AC: 0 AN: 2088

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000116 AC: 1

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hypertrophic cardiomyopathy 10 Uncertain:1

Jun 04, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 77 of the MYL2 protein (p.Ile77Val). This variant is present in population databases (rs373475989, gnomAD 0.0009%). This variant has not been reported in the literature in individuals affected with MYL2-related conditions. ClinVar contains an entry for this variant (Variation ID: 532780). 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: "Benign"; Align-GVGD: "Class C25"). 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.

Hypertrophic cardiomyopathy Uncertain:1

Mar 05, 2024

All of Us Research Program, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces isoleucine with valine at codon 77 of the MYL2 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with MYL2-related disorders in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance.

Cardiovascular phenotype Uncertain:1

Feb 12, 2020

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.I77V variant (also known as c.229A>G), located in coding exon 4 of the MYL2 gene, results from an A to G substitution at nucleotide position 229. The isoleucine at codon 77 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.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.17
CardioboostCm	Uncertain	0.74
BayesDel_addAF	Uncertain	0.078	D
BayesDel_noAF	Benign	-0.13
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Benign	0.33	T
Eigen	Benign	-0.024
Eigen_PC	Benign	0.075
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Uncertain	0.91	D
M_CAP	Benign	0.064	D
MetaRNN	Benign	0.27	T
MetaSVM	Uncertain	-0.21	T
MutationAssessor	Uncertain	2.3	M
PhyloP100		4.8
PrimateAI	Uncertain	0.70	T
PROVEAN	Benign	-0.90	N
REVEL	Uncertain	0.40
Sift	Uncertain	0.015	D
Sift4G	Uncertain	0.037	D
Polyphen		0.0010	B
Vest4		0.42
MVP		0.57
MPC		0.33
ClinPred		0.54	D
GERP RS		4.9
Varity_R		0.55
gMVP		0.71
Mutation Taster		=77/23	polymorphism

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: rs373475989; hg19: chr12-111352035;