MEX3B

Chr 15

mex-3 RNA binding family member B

NCBI Gene: 84206 ENSG00000183496 UniProt: Q6ZN04

MEX3B encodes an RNA-binding phosphoprotein that regulates translation and localizes to processing bodies where it colocalizes with decapping factors and Argonaute proteins. Mutations cause neurodevelopmental disorder with hypotonia and seizures, inherited in an autosomal dominant pattern. The gene shows moderate constraint against loss-of-function variants (LOEUF 0.574), and the associated disorder typically presents in early childhood with developmental delays and neurological features.

ResearchSummary from RefSeq, UniProt

RNA-binding protein. May be involved in post-transcriptional regulatory mechanisms

ResearchGenerating clinical summary…

Clinical highlights

Interpreting a novel variant

This gene is strongly intolerant of loss-of-function variation in the population, so LoF variants warrant close attention. No curated mechanism annotation is available — see the mechanism card for the computational prediction and its caveats.Based on population constraint only.

Active trials

Pubs (1 yr)

—

P/LP submissions

—

P/LP missense

0.57

LOEUF

LOF

Mechanism· predicted

Some data sources returned errors (1)

omim: Error: OMIM fetch failed: 429

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD

Moderate LoF intolerance

LoF Constraint?

0.57LOEUF

pLI 0.555

Z-score 2.51

OE 0.18 (0.07–0.57)

Moderately constrained

More LoF-intolerant than ~75% of genes

Missense Constraint?

1.06Z-score

OE missense 0.84 (0.77–0.93)

298 obs / 353.9 exp

Tolerant

Mild missense constraint

Observed / Expected Ratios?

LoF OE?0.18 (0.07–0.57)

0≤0.351.4

Missense OE?0.84 (0.77–0.93)

0≤0.61.4

Synonymous OE?1.40

0≤1.21.6

LoF obs/exp: 2 / 11.0Missense obs/exp: 298 / 353.9Syn Z: -4.06

Background carrier burden — how many people carry a rare variant somewhere in MEX3B?

gnomAD v4 · ~731k individuals · PASS only

Rare means allele frequency under

Rare missense

1 in 76

1,052 rare PASS variants

Rare truncating (LoF)

1 in 730

168 rare PASS variants

Rare synonymous (reference)

1 in 110

572 rare PASS variants

Truncating variants are far rarer here than missense — that gap, in human units, is what constraint means for MEX3B. A background rate for each class, not the frequency of any particular variant; thin-coverage exons undercount.

By genetic ancestry · 9 gnomAD groups · rare = under 0.1% in that group

Group	People	Missense	Truncating
European (non-Finnish)	~556k	1 in 100	1 in 640
South Asian	~43k	1 in 68	1 in 1,400
Remaining (unassigned)	~30k	1 in 50	1 in 880
European (Finnish)	~27k	1 in 190	1 in 750
Admixed American	~22k	1 in 68	≈ 1 in 5,300
African / African American	~21k	1 in 69	1 in 1,500
East Asian	~20k	1 in 71	1 in 680
Ashkenazi Jewish	~13k	1 in 190	1 in 2,500
Middle Eastern	~2,884	1 in 80	≈ 1 in 950

Each group is summed over the variants that are rare in that group. Grey ≈ figures rest on fewer than five expected carriers — too few to distinguish groups. Differences mostly reflect how many people were sampled and how much variation each ancestry carries, not disease risk.

Exome coverage (gnomAD): All 2 coding exons well covered in gnomAD exomes and genomes.? see exons ↓