3-46858264-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1 PM2

The NM_000258.3(MYL3):c.568A>G(p.Lys190Glu) 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 1,461,882 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MYL3 NM_000258.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 1.93

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 Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a chain Myosin light chain 3 (size 193) in uniprot entity MYL3_HUMAN there are 36 pathogenic changes around while only 6 benign (86%) in NM_000258.3
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MYL3	NM_000258.3	c.568A>G	p.Lys190Glu	missense_variant	6/7	ENST00000292327.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MYL3	ENST00000292327.6	c.568A>G	p.Lys190Glu	missense_variant	6/7	1	NM_000258.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461882 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727242

Gnomad4 AFR exome AF: 0.00

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hypertrophic cardiomyopathy Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	Oct 23, 2023	This missense variant replaces lysine with glutamic acid at codon 190 of the MYL3 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with MYL3-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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Sep 26, 2022	This variant has not been reported in the literature in individuals affected with MYL3-related conditions. 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 are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). ClinVar contains an entry for this variant (Variation ID: 1311228). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces lysine, which is basic and polar, with glutamic acid, which is acidic and polar, at codon 190 of the MYL3 protein (p.Lys190Glu). -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Dec 17, 2019

Has not been previously published as pathogenic or benign to our knowledge; Not observed in large population cohorts (Lek et al., 2016); In silico analysis, which includes protein predictors and evolutionary conservation, supports a deleterious effect -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.71
CardioboostCm	Uncertain	0.11
BayesDel_addAF	Uncertain	0.086	D
BayesDel_noAF	Benign	-0.11
Cadd	Uncertain	25
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.65	D;D
Eigen	Uncertain	0.53
Eigen_PC	Uncertain	0.45
FATHMM_MKL	Pathogenic	0.97	D
M_CAP	Pathogenic	0.30	D
MetaRNN	Uncertain	0.60	D;D
MetaSVM	Uncertain	0.25	D
MutationAssessor	Uncertain	2.6	M;M
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.74	T
PROVEAN	Uncertain	-2.5	D;D
REVEL	Pathogenic	0.68
Sift	Uncertain	0.0010	D;D
Sift4G	Uncertain	0.0030	D;D
Polyphen		0.99	D;D
Vest4		0.39
MutPred		0.48		Loss of methylation at K190 (P = 0.0015);Loss of methylation at K190 (P = 0.0015);
MVP		0.70
MPC		1.1
ClinPred		0.99	D
GERP RS		4.0
Varity_R		0.56
gMVP		0.64

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

Publications

LitVar

Other links and lift over

dbSNP: rs1701953031; hg19: chr3-46899754;