RAB18 deficiency

Summary

RAB18 deficiency (MONDO:0700247) is a disease caused by RAB3GAP2 (GenCC Definitive), with 1 cohort gene.

At a glance

• Causal gene: RAB3GAP2 (GenCC Definitive)
• Cohort genes: 1

Clinical features

No curated clinical features (Orphanet) for this disease.

Identifiers

Disease identifiers

Field	Value
Canonical name	RAB18 deficiency
Mondo ID	MONDO:0700247
UMLS	C4750414
MedGen	1650928
GARD	0026395
Is cancer (heuristic)	no

Also known as: Warburg micro spectrum

Data availability: 1 GenCC gene-disease record.

Disease family

An umbrella term covering 2 Mondo subtypes.

Classification path: disease › human disease › disease by body system or component › syndromic disease › syndromic microphthalmia › RAB18 deficiency

Related subtypes (18): anophthalmia/microphthalmia-esophageal atresia syndrome, COFS syndrome, microphthalmia, syndromic 2, X-linked colobomatous microphthalmia-microcephaly-intellectual disability-short stature syndrome, microphthalmia, syndromic 1, linear skin defects with multiple congenital anomalies, Matthew-Wood syndrome, MMEP syndrome, microphthalmia with brain and digit anomalies, syndromic microphthalmia type 5, microphthalmia-brain atrophy syndrome, oculoauricular syndrome, microphthalmia, syndromic 11, microphthalmia, syndromic 12, colobomatous microphthalmia-rhizomelic dysplasia syndrome, microphthalmia, Lenz type, Behrens Baumann dust syndrome, microphthalmia microtia fetal akinesia

Subtypes (2): Warburg micro syndrome, Martsolf syndrome

Genetics & variants

GWAS landscape

No GWAS associations recorded — common-variant (GWAS) studies don’t cover this disease (typical for Mendelian / rare diseases). See the curated gene cohort and Mendelian overlap below.

Variant details and genetic-evidence tiers

No tiered GWAS variants or ClinVar records for this disease.

Genes & proteins

Mendelian disease overlap and somatic drivers

GenCC: 7 · Orphanet: 3 · OMIM-shared: 0 · Dual-evidence (GWAS+Mendelian): 0

GenCC gene–disease validity (cohort genes)

the Disease column is the GenCC-asserted condition — a cohort gene’s strongest validity may be for a related predisposition syndrome.

Gene	Classification	Inheritance	Disease	Records
RAB3GAP2	Definitive	Autosomal recessive	RAB18 deficiency	7

Orphanet rare-disease linkage (cohort genes)

Gene	Orphanet ID	Rare disease
RAB3GAP2	Orphanet:1387	Cataract-intellectual disability-hypogonadism syndrome
RAB3GAP2	Orphanet:2510	Micro syndrome
RAB3GAP2	Orphanet:401830	Autosomal recessive spastic paraplegia type 69

Cohort genes → proteins

1 cohort genes, 1 distinct canonical proteins.

Evidence partition

Subset	Genes
multi_evidence	1

Cohort genes (full)

Symbol	HGNC	Ensembl	UniProt	Name	Evidence
RAB3GAP2	HGNC:17168	ENSG00000118873	Q9H2M9	Rab3 GTPase-activating protein non-catalytic subunit	gencc

Cohort function summary

Lead sentence per gene, UniProt-curated.

Symbol	Protein name	Function (lead sentence)
RAB3GAP2	Rab3 GTPase-activating protein non-catalytic subunit	Regulatory subunit of the Rab3 GTPase-activating (Rab3GAP) complex composed of RAB3GAP1 and RAB3GAP2, which accelerates the otherwise slow GTP hydrolysis catalyzed by Rab proteins.

Protein-family classification

Druggable: 0 · Difficult: 0 · Unknown: 1 · Druggable fraction: 0.0

Family distribution

Cohort families vs a genome-wide background (hypergeometric, BH-FDR; fold = observed/expected). Counts kept; sorted by enrichment, so the catch-all Other/Unknown bucket no longer leads.

Family	Genes	Fold	FDR
Other/Unknown	1	1.8×	0.558

Per-gene assignment

Symbol	Family	Druggable?	EC	InterPro (top 3)
RAB3GAP2	Other/Unknown	no		Rab3GAP2, RAB3GAP2_C, RAB3GAP_N

Expression context

Cohort genes with no expression data: 0.

1 cohort gene are a single-cell marker in ≥1 SCXA experiment.

Breadth distribution (Bgee present_calls)

Bucket	Genes
narrow (1-5 tissues)	0
moderate (6-20)	0
broad (>20)	1
unknown	0

Top tissues across cohort

Tissue	Cohort genes
choroid plexus epithelium	1
dorsal root ganglion	1
lateral nuclear group of thalamus	1

Per-gene tissue summary (top 30)

Symbol	Bgee breadth	FANTOM5 breadth	SCXA	Top tissues
RAB3GAP2	295	ubiquitous	marker	choroid plexus epithelium, lateral nuclear group of thalamus, dorsal root ganglion

Protein interactions among cohort

Intra-cohort edges: 0.

Hub genes (top 10 by interactor count)

Symbol	Interactor count
RAB3GAP2	1,794

Structural data

PDB: 1 · AlphaFold-only: 0 · No structure: 0

Cohort genes with PDB structures (top 30)

Symbol	UniProt	PDB entries
RAB3GAP2	Q9H2M9	1

Function

Pathway analysis

Distinct Reactome pathways touched by cohort: 2. Enrichment computed across 1 evidence-associated genes (1 with Reactome annotation).

Pathways by enrichment

Over-representation of cohort genes vs the genome-wide background (hypergeometric test, Benjamini-Hochberg FDR; fold = observed/expected over 1 annotated cohort genes). Counts and members are kept as ground-truth; sorted by enrichment.

Pathway	Cohort genes	Fold	FDR	Sample cohort genes
COPI-independent Golgi-to-ER retrograde traffic	1	207.6×	0.008	RAB3GAP2
RAB GEFs exchange GTP for GDP on RABs	1	124.1×	0.008	RAB3GAP2

GO biological processes by enrichment

Over-representation of cohort genes vs the genome-wide background (hypergeometric test, Benjamini-Hochberg FDR; fold = observed/expected over 1 annotated cohort genes). Counts and members are kept as ground-truth; sorted by enrichment.

GO term	Cohort genes	Fold	FDR	Sample cohort genes
establishment of protein localization to endoplasmic reticulum membrane	1	5617.3×	6e-04	RAB3GAP2
positive regulation of protein lipidation	1	4213.0×	6e-04	RAB3GAP2
positive regulation of endoplasmic reticulum tubular network organization	1	4213.0×	6e-04	RAB3GAP2
synaptic signaling	1	1532.0×	0.001	RAB3GAP2
positive regulation of autophagosome assembly	1	802.5×	0.002	RAB3GAP2
regulation of GTPase activity	1	510.7×	0.003	RAB3GAP2
macroautophagy	1	240.7×	0.005	RAB3GAP2
intracellular protein transport	1	64.8×	0.015	RAB3GAP2

Therapeutics

Drug target analysis

Approved (phase 4): 0 · Phase ≥3: 0 · Phased (≥1): 0 · Undrugged: 1

Druggability breadth: 0 of 1 evidence-associated genes (0%) have a ChEMBL target (buckets above are over the deeply-mined display cohort).

Top cohort targets by molecule count

Symbol	Molecules	Max phase
RAB3GAP2	0	0

Bioactivity and enzyme data

Enzyme cohort genes (≥1 EC): 0.

Pharmacogenomics

Cohort genes with a PharmGKB record: 1; with CPIC/DPWG dosing guidelines: 0.

No cohort gene has a CPIC/DPWG genotype-guided dosing guideline (PharmGKB).

Chemical tractability of cohort targets

0 approved/phased compounds have measured bioactivity against a cohort gene (and aren’t yet in disease-level trials). This is a research / tractability signal, NOT a therapeutic recommendation — a bioactivity row often reflects off-target or screening binding (e.g. promiscuous kinase inhibitors against a cohort kinase), implying no disease mechanism.

Druggability pyramid

Cohort genes binned by druggability tier (high → low):

Tier	Definition	Genes	Symbols
A	Approved (phase 4 drug)	0
B	Phased (≥1) drug, not yet approved	0
C	Druggable family + PDB, no drug	0
D	Druggable family + AlphaFold only, no drug	0
E	Difficult family or no structure, no drug	1	RAB3GAP2

Undrugged target profiles

1 cohort genes are undrugged. Ranked by ‘starting-point quality’ (assay depth + drugged-partner adjacency).

Symbol	ChEMBL assays	Drugged partners (top 3)
RAB3GAP2	0	—

Clinical trials & evidence

Clinical trials

Clinical trials: 0.