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FB2026_03
,
released September 17, 2026
Two of the three bromodomain- and WD repeat domain-containing genes in human, PHIP and BRWD3, are implicated in forms of syndromic intellectual disability (see MIM:617991, MIM:300659). The third related gene in human is BRWD1. The functions of these genes are not well characterized; several are known to localize to the nucleus and are thought to play a role in transcriptional regulation. There is a single orthologous gene in Drosophila, Dmel\BRWD3, for which loss-of-function alleles, RNAi-targeting constructs, and alleles caused by insertional mutagenesis have been generated.
None of the human genes (PHIP, BRWD3, BRWD1) has been introduced into flies.
Animals homozygous for amorphic mutations of Dmel\BRWD3 typically die during the pupal stage. In mutant clones in the eye, photoreceptor neurons fail to complete differentiation. Knockdown in classes of neurons, effected by RNAi, results in reduced dendritic branching of the targeted cells. It is postulated that BRWD3 plays a role in transcriptional regulation by controlling the levels of chromatin-associated H3.3 (in flies, Dmel\His3.3A and Dmel\His3.3B). Additional interacting genes have been described; see below and in the Dmel\BRWD3 gene report.
[updated Jan. 2020 by FlyBase; FBrf0222196]
(FlyBase Curators, 2013-)
Intellectual disability can be subdivided into syndromic forms, characterized by cognitive impairment accompanied by dysmorphic features, malformations or neurological abnormalities, and nonsyndromic forms, characterized by cognitive impairment without additional features (Basel-Vanagaite, 2008; DOI: 10.1002/9780470015902.a0021454).
Intellectual disability is characterized by impairments in intellectual functioning and adaptive behavior; symptoms must be present before a child becomes 18 years old (http://medical-dictionary.thefreedictionary.com/mental+retardation; 2016.01.19).
PHIP is a probable regulator of the insulin and insulin-like growth factor signaling pathways. [Gene Cards, PHIP; 2020.01.22]
BRWD1 and BRWD3 play roles in the regulation of cell morphology and cytoskeletal organization and are required in the control of cell shape; may be involved in chromatin remodeling. [Gene Cards, BRWD1, BRWD3; 2020.01.22]
Many to one (3 human to 1 Drosophila).
Many to one (3 human to 1 Drosophila).
Moderate- to high-scoring ortholog of human PHIP, BRWD3 and BRWD1 (1 Drosophila to 3 human). Dmel\BRWD3 shares 34-37% identity and 48-55% similarity with the human genes.