18-3168877-G-T

Variant names:

• chr18-3168877-G-T
• rs376648139
• NM_003803.4:c.1279C>A

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_003803.4(MYOM1):​c.1279C>A​(p.Arg427Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000658 in 152,042 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R427C) has been classified as Uncertain significance.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: MYOM1 NM_003803.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 3.46
• Publications: 5 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: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.17007047).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_003803.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MYOM1	NM_003803.4	MANE Select	c.1279C>A	p.Arg427Ser	missense	Exon 9 of 38	NP_003794.3
	MYOM1	NM_019856.2		c.1279C>A	p.Arg427Ser	missense	Exon 9 of 37	NP_062830.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MYOM1	ENST00000356443.9	TSL:1 MANE Select	c.1279C>A	p.Arg427Ser	missense	Exon 9 of 38	ENSP00000348821.4
	MYOM1	ENST00000261606.11	TSL:1	c.1279C>A	p.Arg427Ser	missense	Exon 9 of 37	ENSP00000261606.7

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 152042 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 33

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 152042 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74254

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 41378

American (AMR) AF: 0.0000655 AC: 1 AN: 15272

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5180

South Asian (SAS) AF: 0.00 AC: 0 AN: 4830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10566

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68030

Other (OTH) AF: 0.00 AC: 0 AN: 2090

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.66
BayesDel_addAF	Benign	-0.12	T
BayesDel_noAF	Benign	-0.41
CADD	Benign	21
DANN	Benign	0.97
DEOGEN2	Benign	0.033	T
Eigen	Benign	-0.52
Eigen_PC	Benign	-0.26
FATHMM_MKL	Uncertain	0.76	D
LIST_S2	Uncertain	0.89	D
M_CAP	Benign	0.013	T
MetaRNN	Benign	0.17	T
MetaSVM	Benign	-0.99	T
MutationAssessor	Benign	-1.6	N
PhyloP100		3.5
PrimateAI	Benign	0.48	T
PROVEAN	Benign	0.72	N
REVEL	Benign	0.064
Sift	Benign	0.67	T
Sift4G	Benign	0.70	T
Polyphen		0.0040	B
Vest4		0.16
MutPred		0.63		Loss of catalytic residue at R427 (P = 0.1144)
MVP		0.73
MPC		0.17
ClinPred		0.83	D
GERP RS		3.8
Varity_R		0.16
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

Other links and lift over

dbSNP: rs376648139; hg19: chr18-3168875;