ARID1B

AT-rich interaction domain 1B

2 disorders 1 untyped 1 no genetic record 6q25.3 gene with protein product

HGNC:18040 Monarch NCBI Gene 57492 ENSG00000049618 UniProt Q8NFD5 OMIM 614556

Aliases: KIAA1235, ELD/OSA1, p250R, BAF250b, DAN15, 6A3-5, SMARCF2.

Normal function · from ai-gene-review (Q8NFD5, commit 79fe13b38970) · AI-generated, not KB evidence

ARID1B (BAF250B/p250R) is a nuclear DNA-binding and assembly subunit of canonical mammalian SWI/SNF chromatin-remodeling complexes. Its ARID region binds DNA without an established sequence preference, and other regions associate with the SMARCA2 or SMARCA4 ATPase and additional complex subunits. ARID1B and ARID1A are mutually exclusive alternatives in these assemblies, coupling DNA engagement and regulatory recruitment to ATP-dependent nucleosome remodeling. Human ARID1B also supports steroid-receptor transcriptional coactivation in tested cellular contexts. ARID1B-dependent gene regulation is important in development, and pathogenic loss of function causes Coffin–Siris syndrome.

ARID1B binds DNA without apparent sequence preference and supplies assembly contacts to human SWI/SNF complexes, contributing to cooperative nucleosome engagement and ATP-driven chromatin remodeling. SMARCA2 or SMARCA4 provides the ATPase.

molecular function: DNA binding · contributes to molecular function: ATP-dependent chromatin remodeler activity · directly involved in: chromatin remodeling · locations: nucleoplasm · in complex: SWI/SNF complex

Human hOsa2/ARID1B supports transcriptional coactivation by steroid receptors as part of SWI/SNF, with an intact DNA-binding region required in the tested GR reporter context. Reporter conditions distinguish human ARID1B from rat GR and human ER/AR reagents.

molecular function: transcription coactivator activity · directly involved in: positive regulation of DNA-templated transcription · locations: nucleoplasm · in complex: SWI/SNF complex

In the knowledge base · computed from kb/ at build time

Disorders

Relationship is the entry's genetic[].relationship_type. untyped means the entry has a genetic record for the gene but does not type it; its free-text association is shown instead.

Disorder	Relationship	Where the gene appears
Coffin-Siris syndrome	untyped Causative	mechanism: Altered cell-cycle dynamics from ARID1B haploinsufficiency; BAF/SWI-SNF chromatin remodeling dysfunction; Corpus callosum projection neuron axonogenesis defect from ARID1B haploinsufficiency; Cortical interneuron deficiency from ARID1B haploinsufficiency; IGF1/GH axis dysregulation in ARID1B haploinsufficiency; Mesenchymal stem cell quiescence loss and tooth root progenitor defects; Protein misfolding and aggregation of non-truncating ARID1B variants subtype: CSS1 scoped to subtype: CSS1
Salivary Gland Polymorphous Adenocarcinoma	no genetic record somatic	mechanism: PRKD Family Gene Rearrangement

ClinGen gene–disease validity · snapshot 2026-10-03 · matched to entries by MONDO

An entry matches when ClinGen's MONDO disease is the entry's own disease term, a subtype term, or an exact-match mapping. An amber status marks an entry ClinGen supports the gene for (Definitive, Strong or Moderate) whose own record does not type it. A Limited, Disputed or Refuted tier on such an entry is not a gap.

ClinGen disease	MOI	Classification	dismech entry
Coffin-Siris syndrome MONDO:0015452	AD	Definitive 2019-12-04	Coffin-Siris syndrome untyped

Mechanism modules · computed from kb/

epigenetic_machinery_neurodevelopmental_dysregulation via Coffin-Siris syndrome
projection_neuron_subtype_specification via Coffin-Siris syndrome

Identity from HGNC (snapshot 2026-10-01). Page layers are described in the gene pages documentation.