BTBD18

Chr 11

BTB domain containing 18

NCBI Gene: 643376 ENSG00000233436 UniProt: B2RXH4

Predicted to be involved in several processes, including male meiosis I; piRNA transcription; and transposable element silencing. Predicted to be active in nucleus. [provided by Alliance of Genome Resources, Jun 2026]

Research

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

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P/LP missense

0.21

LOEUF· LoF intol.

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

LoF intolerant — likely haploinsufficient

LoF Constraint?

0.21LOEUF

pLI 0.998

Z-score 4.18

OE 0.04 (0.01–0.21)

Highly constrained

Highly LoF-intolerant (top ~10% of genes)

Missense Constraint?

1.65Z-score

OE missense 0.76 (0.69–0.84)

280 obs / 369.3 exp

Tolerant

Mild missense constraint

Observed / Expected Ratios?

LoF OE?0.04 (0.01–0.21)

0≤0.351.4

Missense OE?0.76 (0.69–0.84)

0≤0.61.4

Synonymous OE?0.77

0≤1.21.6

LoF obs/exp: 1 / 22.3Missense obs/exp: 280 / 369.3Syn Z: 2.15

Background carrier burden — how many people carry a rare variant somewhere in BTBD18?

gnomAD v4 · ~700k individuals · PASS only

Rare means allele frequency under

Rare missense

1 in 69

852 rare PASS variants

Rare truncating (LoF)

1 in 1,500

53 rare PASS variants

Rare synonymous (reference)

1 in 95

337 rare PASS variants

Truncating variants are far rarer here than missense — that gap, in human units, is what constraint means for BTBD18. 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)	~539k	1 in 130	1 in 6,100
South Asian	~40k	1 in 57	1 in 2,200
Remaining (unassigned)	~29k	1 in 77	1 in 2,100
European (Finnish)	~25k	1 in 190	none seen
African / African American	~21k	1 in 71	≈ 1 in 4,800
East Asian	~18k	1 in 64	1 in 2,200
Admixed American	~18k	1 in 65	≈ 1 in 18,000
Ashkenazi Jewish	~13k	1 in 180	none seen
Middle Eastern	~2,849	1 in 75	none seen

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 ↓