CABP4

Chr 11

calcium binding protein 4

Also known as: CRSD, CSNB2B

NCBI Gene: 57010 ENSG00000175544 UniProt: P57796

This gene encodes a calcium-binding protein that regulates calcium influx and neurotransmitter release at photoreceptor synaptic terminals by modulating calcium channels. Mutations cause congenital stationary night blindness type 2B (cone-rod synaptic disorder), an autosomal recessive condition affecting retinal function from birth. The gene is not highly constrained against loss-of-function variants, consistent with its recessive inheritance pattern.

GeneReviews ResearchSummary from RefSeq, OMIM, UniProt

This gene encodes a member of the CABP family of calcium binding protein characterized by four EF-hand motifs. Mutations in this gene are associated with congenital stationary night blindness type 2B. Three transcript variants encoding two different isoforms have been found for this gene. [provided by RefSeq, Jul 2014]

GeneReviews ResearchGenerating clinical summary…

Primary Disease Associations & Inheritance

UniProtCone-rod synaptic disorder, congenital non-progressive

Clinical highlights

Gene–disease validity (ClinGen)

Definitive · cone-rod synaptic disorder, congenital nonprogressive · AR · ClinGen 2026

Interpreting a novel variant

Loss of function is the curated mechanism (Gene2Phenotype), though the gene is not strongly LoF-constrained in the population — weigh truncating variants against that tolerance.Curated gene-level mechanism — a prior for triage, not a per-variant call.

Active trials

Pubs (1 yr)

—

P/LP submissions

—

P/LP missense

1.54

LOEUF

LOF

Mechanism· G2P

📖

GeneReview available — CABP4

Authoritative clinical overview · Recommended first read

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Some data sources returned errors (1)

omim: Error: OMIM fetch failed: 429

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD

Tolerant — LoF & missense variants common in population

LoF Constraint?

1.54LOEUF

pLI 0.000

Z-score -0.02

OE 1.00 (0.67–1.54)

Tolerant

Highly tolerant — LoF variants common in population

Missense Constraint?

-0.52Z-score

OE missense 1.11 (0.99–1.24)

208 obs / 188.0 exp

Tolerant

Tolerant to missense variation

Observed / Expected Ratios?

LoF OE?1.00 (0.67–1.54)

0≤0.351.4

Missense OE?1.11 (0.99–1.24)

0≤0.61.4

Synonymous OE?1.03

0≤1.21.6

LoF obs/exp: 15 / 14.9Missense obs/exp: 208 / 188.0Syn Z: -0.19

Background carrier burden — how many people carry a rare variant somewhere in CABP4?

gnomAD v4 · ~731k individuals · PASS only

Rare means allele frequency under

Rare missense

1 in 74

468 rare PASS variants

Rare truncating (LoF)

1 in 1,000

85 rare PASS variants

Rare synonymous (reference)

1 in 190

179 rare PASS variants

Truncating variants are far rarer here than missense — that gap, in human units, is what constraint means for CABP4. 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 99	1 in 920
South Asian	~43k	1 in 98	1 in 2,100
Remaining (unassigned)	~30k	1 in 70	1 in 940
European (Finnish)	~27k	1 in 150	1 in 1,800
Admixed American	~22k	1 in 73	1 in 1,200
African / African American	~21k	1 in 110	1 in 1,300
East Asian	~20k	1 in 110	1 in 1,400
Ashkenazi Jewish	~13k	1 in 1,400	≈ 1 in 4,300
Middle Eastern	~2,884	1 in 78	≈ 1 in 960

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 6 coding exons well covered in gnomAD exomes and genomes.? see exons ↓