NM_032608.7:c.6660_6670delATTAGAACCTG

Variant names:

• chr22-26026632-AGATTAGAACCT-A
• rs756408696
• NM_032608.7:c.6660_6670delATTAGAACCTG

Variant summary

Our verdict is Pathogenic. The variant received 20 ACMG points: 20P and 0B. PVS1 PS3 PP5_Very_Strong

The NM_032608.7(MYO18B):​c.6660_6670delATTAGAACCTG​(p.Arg2220SerfsTer74) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000141 in 1,613,568 control chromosomes in the GnomAD database, with no homozygous occurrence. It is difficult to determine the true allele frequency of this variant because it is of type DEL_BIG, and the frequency of such variant types in population databases may be underestimated and unreliable. Variant has been reported in ClinVar as Likely pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV000844943: Characterization of the effect of a premature stop of translation within MYO18B has been described in the setting of in-vitro analyses. Examination of an affected patient's lymphocytes harboring a nonsense alteration (p.Ser2303Ter) demonstrated markedly diminished MYO18B transcript by quantitative PCR in comparison to a control, therefore hypothesized to be consistent with nonsense-mediated decay (PMID:25748484). Moreover, western blot analysis and immunostaining of skeletal muscle in another patient harboring a nonsense alteration (p.Glu2166Ter) demonstrated the absence of the C-terminus of the protein hypothesized to be consistent with protein truncation (PMID:27858739).". Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00015 (0 hom.)
• Consequence: MYO18B NM_032608.7 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:7
• Conservation: PhyloP100: 3.40
• Publications: 2 publications found

Genes affected

MYO18B (HGNC:18150): (myosin XVIIIB) The protein encoded by this gene may regulate muscle-specific genes when in the nucleus and may influence intracellular trafficking when in the cytoplasm. The encoded protein functions as a homodimer and may interact with F actin. Mutations in this gene are associated with lung cancer. [provided by RefSeq, Jul 2008]

MYO18B Gene-Disease associations (from GenCC):

• Klippel-Feil anomaly-myopathy-facial dysmorphism syndrome

  Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: ClinGen, Orphanet, Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P

ACMG classification

Our verdict: Pathogenic. The variant received 20 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PS3: PS3 evidence extracted from ClinVar submissions: SCV000844943: Characterization of the effect of a premature stop of translation within MYO18B has been described in the setting of in-vitro analyses. Examination of an affected patient's lymphocytes harboring a nonsense alteration (p.Ser2303Ter) demonstrated markedly diminished MYO18B transcript by quantitative PCR in comparison to a control, therefore hypothesized to be consistent with nonsense-mediated decay (PMID: 25748484). Moreover, western blot analysis and immunostaining of skeletal muscle in another patient harboring a nonsense alteration (p.Glu2166Ter) demonstrated the absence of the C-terminus of the protein hypothesized to be consistent with protein truncation (PMID: 27858739).
• PP5: Variant 22-26026632-AGATTAGAACCT-A is Pathogenic according to our data. Variant chr22-26026632-AGATTAGAACCT-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 590293.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_032608.7. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MYO18B	NM_032608.7	MANE Select	c.6660_6670delATTAGAACCTG	p.Arg2220SerfsTer74	frameshift	Exon 43 of 44	NP_115997.5
	MYO18B	NM_001318245.2		c.6663_6673delATTAGAACCTG	p.Arg2221SerfsTer74	frameshift	Exon 43 of 44	NP_001305174.1	Q8IUG5-3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MYO18B	ENST00000335473.12	TSL:1 MANE Select	c.6660_6670delATTAGAACCTG	p.Arg2220SerfsTer74	frameshift	Exon 43 of 44	ENSP00000334563.8	Q8IUG5-1
	MYO18B	ENST00000407587.6	TSL:1	c.6663_6673delATTAGAACCTG	p.Arg2221SerfsTer74	frameshift	Exon 43 of 44	ENSP00000386096.2	Q8IUG5-3
	MYO18B	ENST00000536101.5	TSL:1	c.6660_6670delATTAGAACCTG	p.Arg2220SerfsTer74	frameshift	Exon 43 of 43	ENSP00000441229.1	Q8IUG5-1

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 151914 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.0000441

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000442 AC: 11 AN: 248956 AF XY: 0.0000444

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000975

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.000154 AC: 225 AN: 1461654 Hom.: 0 AF XY: 0.000161 AC XY: 117 AN XY: 727118

African (AFR) AF: 0.0000299 AC: 1 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53358

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

European-Non Finnish (NFE) AF: 0.000197 AC: 219 AN: 1111858

Other (OTH) AF: 0.0000828 AC: 5 AN: 60374

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 151914 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74178

African (AFR) AF: 0.00 AC: 0 AN: 41338

American (AMR) AF: 0.00 AC: 0 AN: 15254

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5168

South Asian (SAS) AF: 0.00 AC: 0 AN: 4780

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10590

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

European-Non Finnish (NFE) AF: 0.0000441 AC: 3 AN: 67994

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

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000378

EpiCase AF: 0.00

EpiControl AF: 0.000119

ClinVar

ClinVar submissions

Significance: Pathogenic/Likely pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
5	-	-	Klippel-Feil anomaly-myopathy-facial dysmorphism syndrome (5)
2	-	-	not provided (2)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		3.4
Mutation Taster		=18/182	disease causing (ClinVar)

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs756408696; hg19: chr22-26422598;