18-3067279-C-T

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_003803.4(MYOM1):c.5041G>A(p.Gly1681Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000207 in 1,451,620 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict 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. G1681R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: MYOM1 NM_003803.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.256

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]

ACMG classification

Verdict is Likely_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.03233829).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MYOM1	NM_003803.4	c.5041G>A	p.Gly1681Ser	missense_variant	38/38	ENST00000356443.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MYOM1	ENST00000356443.9	c.5041G>A	p.Gly1681Ser	missense_variant	38/38	1	NM_003803.4	P2
MYOM1	ENST00000261606.11	c.4753G>A	p.Gly1585Ser	missense_variant	37/37	1		A2
MYOM1	ENST00000581804.1	n.531G>A		non_coding_transcript_exon_variant	3/3	3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000207 AC: 3 AN: 1451620 Hom.: 0 Cov.: 29 AF XY: 0.00000139 AC XY: 1 AN XY: 721174

Gnomad4 AFR exome AF: 0.0000301

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: 0.00000181

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 30, 2022

The p.G1681S variant (also known as c.5041G>A), located in coding exon 37 of the MYOM1 gene, results from a G to A substitution at nucleotide position 5041. The glycine at codon 1681 is replaced by serine, an amino acid with similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be tolerated 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	Benign	0.14
BayesDel_addAF	Benign	-0.38	T
BayesDel_noAF	Benign	-0.78
Cadd	Benign	4.0
Dann	Benign	0.48
DEOGEN2	Benign	0.020	T;.;.
Eigen	Benign	-1.4
Eigen_PC	Benign	-1.4
FATHMM_MKL	Benign	0.031	N
LIST_S2	Benign	0.62	T;T;T
M_CAP	Benign	0.0048	T
MetaRNN	Benign	0.032	T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.2	L;.;.
MutationTaster	Benign	1.0	N;N;N
PrimateAI	Benign	0.23	T
PROVEAN	Benign	0.36	N;.;N
REVEL	Benign	0.0030
Sift	Benign	0.60	T;.;T
Sift4G	Benign	0.48	T;T;T
Polyphen		0.0	B;.;B
Vest4		0.020
MutPred		0.35		Gain of phosphorylation at G1681 (P = 0.0048);.;.;
MVP		0.11
MPC		0.14
ClinPred		0.045	T
GERP RS		-1.6
Varity_R		0.024
gMVP		0.51

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: rs769553242; hg19: chr18-3067277;