chr3-46859532-T-C

Position:

• chr3-46859532-T-C

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_000258.3(MYL3):​c.424A>G​(p.Lys142Glu) 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 (★). Synonymous variant affecting the same amino acid position (i.e. K142K) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MYL3 NM_000258.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:2
• Conservation: PhyloP100: 8.02

Genes affected

MYL3 (HGNC:7584): (myosin light chain 3) MYL3 encodes myosin light chain 3, an alkali light chain also referred to in the literature as both the ventricular isoform and the slow skeletal muscle isoform. Mutations in MYL3 have been identified as a cause of mid-left ventricular chamber type hypertrophic cardiomyopathy. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 9 uncertain in NM_000258.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.947

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MYL3	NM_000258.3	c.424A>G	p.Lys142Glu	missense_variant	4/7	ENST00000292327.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MYL3	ENST00000292327.6	c.424A>G	p.Lys142Glu	missense_variant	4/7	1	NM_000258.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, no assertion criteria provided

provider interpretation

Stanford Center for Inherited Cardiovascular Disease, Stanford University

Aug 23, 2017

Present in an individual with HCM at our center. Testing was performed at Invitae. Given the lack of case data and absence in population databases, we consider this variant a variant of uncertain significance and we do not feel it is suitable for assessing risk in healthy relatives ("predictive genetic testing"). I could find no reports of the variant in the literature (per Google and PubMed). Per the lab report: "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, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain." The variant is not listed in the Genome Aggregation Consortium Dataset (gnomAD; http://gnomad.broadinstitute.org/), which currently includes variant calls on >140,000 unrelated individuals of African, Asian, European, Latino, and Ashkenazi descent. The average coverage at that site in gnomAD is 92x in exomes and 35x in genomes. -

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Dec 27, 2018

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. 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, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with MYL3-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change replaces lysine with glutamic acid at codon 142 of the MYL3 protein (p.Lys142Glu). The lysine residue is highly conserved and there is a small physicochemical difference between lysine and glutamic acid. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
CardioboostCm	Uncertain	0.73
BayesDel_addAF	Pathogenic	0.41	D
BayesDel_noAF	Pathogenic	0.35
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.75	D;D
Eigen	Pathogenic	0.77
Eigen_PC	Pathogenic	0.69
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Benign	0.84	.;T
M_CAP	Pathogenic	0.38	D
MetaRNN	Pathogenic	0.95	D;D
MetaSVM	Uncertain	0.78	D
MutationAssessor	Pathogenic	3.3	M;M
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.88	D
PROVEAN	Uncertain	-4.0	D;D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.013	D;D
Sift4G	Pathogenic	0.0010	D;D
Polyphen		1.0	D;D
Vest4		0.83
MutPred		0.79		Loss of ubiquitination at K142 (P = 0.0199);Loss of ubiquitination at K142 (P = 0.0199);
MVP		0.92
MPC		1.3
ClinPred		1.0	D
GERP RS		4.3
Varity_R		0.90
gMVP		0.88

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: rs1553639863; hg19: chr3-46901022;