18-3151790-G-A

Variant names:

• chr18-3151790-G-A
• rs765191680
• NM_003803.4:c.1747C>T

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 0P and 4B. BS2

The NM_003803.4(MYOM1):​c.1747C>T​(p.Arg583*) variant causes a stop gained change. The variant allele was found at a frequency of 0.00000547 in 1,461,622 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000055 (0 hom.)
• Consequence: MYOM1 NM_003803.4 stop_gained
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.73
• Publications: 1 publications found

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]

MYOM1 Gene-Disease associations (from GenCC):

• hypertrophic cardiomyopathy

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Likely_benign. The variant received -4 ACMG points.

• BS2: High AC in GnomAdExome4 at 8 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MYOM1	NM_003803.4	c.1747C>T	p.Arg583*	stop_gained	Exon 12 of 38	ENST00000356443.9	NP_003794.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MYOM1	ENST00000356443.9	c.1747C>T	p.Arg583*	stop_gained	Exon 12 of 38	1	NM_003803.4	ENSP00000348821.4
MYOM1	ENST00000261606.11	c.1747C>T	p.Arg583*	stop_gained	Exon 12 of 37	1		ENSP00000261606.7

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.0000201 AC: 5 AN: 249178 AF XY: 0.0000148

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000116

Gnomad ASJ exome AF: 0.0000994

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000547 AC: 8 AN: 1461622 Hom.: 0 Cov.: 31 AF XY: 0.00000550 AC XY: 4 AN XY: 727098

African (AFR) AF: 0.00 AC: 0 AN: 33476

American (AMR) AF: 0.0000894 AC: 4 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.00 AC: 0 AN: 86250

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53396

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

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111814

Other (OTH) AF: 0.0000331 AC: 2 AN: 60372

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000508 Hom.: 0

Bravo AF: 0.0000151

ExAC AF: 0.0000248 AC: 3

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hypertrophic cardiomyopathy Uncertain:1

Jul 15, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Arg583*) in the MYOM1 gene. It is expected to result in an absent or disrupted protein product. However, the current clinical and genetic evidence is not sufficient to establish whether loss-of-function variants in MYOM1 cause disease. This variant is present in population databases (rs765191680, gnomAD 0.01%). This variant has not been reported in the literature in individuals affected with MYOM1-related conditions. ClinVar contains an entry for this variant (Variation ID: 410231). 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.62
CADD	Pathogenic	41
DANN	Uncertain	1.0
Eigen	Uncertain	0.52
Eigen_PC	Uncertain	0.36
FATHMM_MKL	Uncertain	0.88	D
PhyloP100		5.7
Vest4		0.53
GERP RS		3.1
Mutation Taster		=9/191	disease causing (fs/PTC)

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: rs765191680; hg19: chr18-3151788;