13-48233446-T-TC

Variant names:

• chr13-48233446-T-TC
• rs746700992
• NM_021999.5:c.93dupC

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PVS1_Strong

The NM_021999.5(ITM2B):​c.93dupC​(p.Asp32ArgfsTer12) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000131 in 1,532,134 control chromosomes in the GnomAD database, with no homozygous occurrence. There is a variant allele frequency bias in the population database for this variant (GnomAdExome4), which may indicate mosaicism or somatic mutations in the reference population data. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.0000067 (0 hom., cov: 31)
  • Exomes 𝑓: 0.000014 (0 hom.)
• Consequence: ITM2B NM_021999.5 frameshift
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: -0.168
• Publications: 1 publications found

Genes affected

ITM2B (HGNC:6174): (integral membrane protein 2B) Amyloid precursor proteins are processed by beta-secretase and gamma-secretase to produce beta-amyloid peptides which form the characteristic plaques of Alzheimer disease. This gene encodes a transmembrane protein which is processed at the C-terminus by furin or furin-like proteases to produce a small secreted peptide which inhibits the deposition of beta-amyloid. Mutations which result in extension of the C-terminal end of the encoded protein, thereby increasing the size of the secreted peptide, are associated with two neurogenerative diseases, familial British dementia and familial Danish dementia. [provided by RefSeq, Oct 2009]

ITM2B Gene-Disease associations (from GenCC):

• ABri amyloidosis

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet
• ADan amyloidosis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• retinal dystrophy with inner retinal dysfunction and ganglion cell anomalies

  Inheritance: AD Classification: SUPPORTIVE, LIMITED Submitted by: Orphanet, G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 4 pathogenic variants in the truncated region.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_021999.5. 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
	ITM2B	NM_021999.5	MANE Select	c.93dupC	p.Asp32ArgfsTer12	frameshift	Exon 1 of 6	NP_068839.1	Q9Y287-1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ITM2B	ENST00000647800.2	MANE Select	c.93dupC	p.Asp32ArgfsTer12	frameshift	Exon 1 of 6	ENSP00000497221.1	Q9Y287-1
	ITM2B	ENST00000970638.1		c.93dupC	p.Asp32ArgfsTer12	frameshift	Exon 1 of 7	ENSP00000640697.1
	ITM2B	ENST00000899433.1		c.93dupC	p.Asp32ArgfsTer12	frameshift	Exon 1 of 6	ENSP00000569492.1

Frequencies

GnomAD3 genomes AF: 0.00000665 AC: 1 AN: 150294 Hom.: 0 Cov.: 31

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: 0.0000148

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000586 AC: 8 AN: 136534 AF XY: 0.0000802

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000462

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000249

Gnomad FIN exome AF: 0.0000640

Gnomad NFE exome AF: 0.0000542

Gnomad OTH exome AF: 0.000279

GnomAD4 exome AF: 0.0000137 AC: 19 AN: 1381840 Hom.: 0 Cov.: 30 AF XY: 0.0000132 AC XY: 9 AN XY: 683182

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

African (AFR) AF: 0.00 AC: 0 AN: 28542

American (AMR) AF: 0.0000293 AC: 1 AN: 34116

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 24140

East Asian (EAS) AF: 0.0000303 AC: 1 AN: 33006

South Asian (SAS) AF: 0.00 AC: 0 AN: 77024

European-Finnish (FIN) AF: 0.0000617 AC: 3 AN: 48586

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5598

European-Non Finnish (NFE) AF: 0.0000102 AC: 11 AN: 1073762

Other (OTH) AF: 0.0000526 AC: 3 AN: 57066

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.00000000000310108), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome AF: 0.00000665 AC: 1 AN: 150294 Hom.: 0 Cov.: 31 AF XY: 0.0000136 AC XY: 1 AN XY: 73342

African (AFR) AF: 0.00 AC: 0 AN: 40704

American (AMR) AF: 0.00 AC: 0 AN: 15152

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3456

East Asian (EAS) AF: 0.00 AC: 0 AN: 5100

South Asian (SAS) AF: 0.00 AC: 0 AN: 4710

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10352

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 314

European-Non Finnish (NFE) AF: 0.0000148 AC: 1 AN: 67532

Other (OTH) AF: 0.00 AC: 0 AN: 2068

Alfa AF: 0.00 Hom.: 1

Bravo AF: 0.00000378

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	2	-	not provided (2)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		-0.17
Mutation Taster		=9/191	disease causing (fs/PTC)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs746700992; hg19: chr13-48807582;