rs1555629260

chr18-3193854-A-C

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2 BP4

The NM_003803.4(MYOM1):c.395T>G(p.Leu132Trp) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. 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. L132F) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MYOM1 NM_003803.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.05

Genes affected

MYOM1 (HGNC:7613): (myomesin 1) The giant protein titin, together with its associated proteins, interconnects the major structure of sarcomeres, the M bands and Z discs. The C-terminal end of the titin string extends into the M line, where it binds tightly to M-band constituents of apparent molecular masses of 190 kD (myomesin 1) and 165 kD (myomesin 2). This protein, myomesin 1, like myomesin 2, titin, and other myofibrillar proteins contains structural modules with strong homology to either fibronectin type III (motif I) or immunoglobulin C2 (motif II) domains. Myomesin 1 and myomesin 2 each have a unique N-terminal region followed by 12 modules of motif I or motif II, in the arrangement II-II-I-I-I-I-I-II-II-II-II-II. The two proteins share 50% sequence identity in this repeat-containing region. The head structure formed by these 2 proteins on one end of the titin string extends into the center of the M band. The integrating structure of the sarcomere arises from muscle-specific members of the superfamily of immunoglobulin-like proteins. Alternatively spliced transcript variants encoding different isoforms have been identified. [provided by RefSeq, Jul 2008]

(HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.3320098).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MYOM1	NM_003803.4	c.395T>G	p.Leu132Trp	missense_variant	3/38	ENST00000356443.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MYOM1	ENST00000356443.9	c.395T>G	p.Leu132Trp	missense_variant	3/38	1	NM_003803.4	P2
MYOM1	ENST00000261606.11	c.395T>G	p.Leu132Trp	missense_variant	3/37	1		A2
	ENST00000580139.1	n.121-22A>C		intron_variant, non_coding_transcript_variant		2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Dec 17, 2017

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 do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with MYOM1-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change replaces leucine with tryptophan at codon 132 of the MYOM1 protein (p.Leu132Trp). The leucine residue is weakly conserved and there is a small physicochemical difference between leucine and tryptophan. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.46
BayesDel_addAF	Benign	-0.10	T
BayesDel_noAF	Benign	-0.38
Cadd	Uncertain	24
Dann	Benign	0.95
DEOGEN2	Benign	0.020	T;.
Eigen	Benign	0.13
Eigen_PC	Benign	0.12
FATHMM_MKL	Benign	0.62	D
LIST_S2	Benign	0.73	T;T
M_CAP	Benign	0.033	D
MetaRNN	Benign	0.33	T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.5	L;L
MutationTaster	Benign	1.0	N;N;N
PrimateAI	Benign	0.28	T
PROVEAN	Benign	-0.83	N;N
REVEL	Benign	0.12
Sift	Uncertain	0.029	D;D
Sift4G	Uncertain	0.025	D;D
Polyphen		0.96	D;D
Vest4		0.47
MutPred		0.34		Loss of stability (P = 0.0399);Loss of stability (P = 0.0399);
MVP		0.87
MPC		0.62
ClinPred		0.59	D
GERP RS		4.7
Varity_R		0.062
gMVP		0.28

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: rs1555629260; hg19: chr18-3193852;