ITM2B

Chr 13AD

integral membrane protein 2B

Also known as: ABRI, BRI, BRI2, BRICD2B, E25B, E3-16, FBD, RDGCA

ITM2B encodes a transmembrane protein that inhibits amyloid-beta peptide aggregation and regulates processing of amyloid precursor protein, while also promoting neurite outgrowth. Mutations cause autosomal dominant familial British dementia, familial Danish dementia, and retinal dystrophy with inner retinal dysfunction and ganglion cell abnormalities. The gene shows high constraint against loss-of-function variants (LOEUF 0.536), indicating intolerance to protein-truncating mutations.

Summary from RefSeq, OMIM, UniProt
Research Assistant →

Primary Disease Associations & Inheritance

?Retinal dystrophy with inner retinal dysfunction and ganglion cell abnormalitiesMIM #616079
AD
Dementia, familial BritishMIM #176500
AD
Dementia, familial DanishMIM #117300
AD
UniProtCerebral amyloid angiopathy, ITM2B-related 1
UniProtCerebral amyloid angiopathy, ITM2B-related 2
0
Active trials
14
Pubs (1 yr)
75
P/LP submissions
1%
P/LP missense
0.54
LOEUF
LOF
Mechanism· predicted
Clinical SummaryITM2B
Population Constraint (gnomAD)
Moderately constrained gene (pLI 0.63) — some intolerance to loss-of-function variants.
📋
ClinVar Variants
74 unique Pathogenic / Likely Pathogenic· 116 VUS of 261 total submissions

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Moderate LoF intolerance
LoF Constraint
0.54LOEUF
pLI 0.626
Z-score 2.64
OE 0.17 (0.070.54)
Moderately constrained

More LoF-intolerant than ~75% of genes

Missense Constraint
1.04Z-score
OE missense 0.75 (0.640.89)
107 obs / 141.9 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios
LoF OE0.17 (0.070.54)
00.351.4
Missense OE0.75 (0.640.89)
00.61.4
Synonymous OE0.84
01.21.6
LoF obs/exp: 2 / 11.8Missense obs/exp: 107 / 141.9Syn Z: 0.87
Curated Mechanism (G2P)Gene2Phenotype (DDG2P) ↗
limitedITM2B-related retinal dystrophy with inner retinal dysfunction and ganglion cell abnormalitiesOTHERAD
DN
0.3892th %ile
GOF
0.4578th %ile
LOF
0.4726th %ile

The highest-scoring mechanism for this gene is loss-of-function (haploinsufficiency).

LOF1 literature citation

Literature Evidence

LOFMutations in integral membrane protein 2B (ITM2b/BRI2) gene cause familial British and Danish dementia (FBD and FDD), autosomal dominant disorders characterized by progressive cognitive deterioration. Two pathogenic mechanisms, which may not be mutually exclusive, have been proposed for FDD and FBD:PMID:33172889

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.

ClinVar Variant Classifications

261 submitted variants in ClinVar

Classification Summary

Pathogenic71
Likely Pathogenic3
VUS116
Likely Benign52
Benign5
Conflicting4
71
Pathogenic
3
Likely Pathogenic
116
VUS
52
Likely Benign
5
Benign
4
Conflicting

Curated Variants Distribution

Classified variants from ClinVar · 5 ACMG categories

ClassificationLoFMissense + InframeNon-codingSynonymousTotal
Pathogenic
2
1
68
0
71
Likely Pathogenic
1
0
2
0
3
VUS
6
95
15
0
116
Likely Benign
0
1
15
36
52
Benign
0
1
0
4
5
Conflicting
4
Total99810040251

LoF = frameshift, stop gained/lost, canonical splice · Counts from ClinVar esearch · Updated hourly

View in ClinVar →

Protein Context — Lollipop Plot

ITM2B · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

No active trials found for this gene.

Search ClinicalTrials.gov →
Clinical Literature
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