This report describes GAND syndrome (GAND), previously intellectual disability, autosomal dominant 18 or mental retardation, autosomal dominant 18 (MRD18). The human gene implicated in this disease is GATAD2B (GATA zinc finger domain-containing protein 2B) which is a transcriptional repressor. There is a second similar gene in humans, GATAD2A. There is a single Drosophila ortholog, Dmel\simj, for which classical loss-of-function alleles, RNAi-targeting constructs, and alleles caused by insertional mutagenesis have been generated.
The human GATAD2B gene has not been introduced into flies.
Pan-neuronal expression of RNAi targeted against Dmel\simj results in learning defective phenotypes in adults. If RNAi effects are enhanced, defects in neuromuscular junctions are observed in third instar larvae. Physical interaction(s) of the Dmel\simj protein product have been described; see below and in the FlyBase gene report for simj.
[updated Jun. 2022 by FlyBase; FBrf0222196]
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).
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).
[GAND SYNDROME; GAND](https://omim.org/entry/615074)
[GATA ZINC FINGER DOMAIN-CONTAINING PROTEIN 2B; GATAD2B](https://omim.org/entry/614998)
Patients with MRD18 exhibit severe intellectual disability, global developmental delay, and dysmorphic features.
In three unrelated patients with severe intellectual disability and similar dysmorphic features, heterozygous truncating mutations in the GATAD2B gene were identified (de Ligt et al., 2012, pubmed:23033978; Willemsen et al., 2013, pubmed:23644463). [from MIM:615074; 2016.01.25]
GATAD2B (GATA zinc finger domain-containing protein 2B) is a subunit of the methyl-CpG-binding protein-1 complex (MeCP1), which deacetylates methylated nucleosomes to repress transcription (summary by Brackertz et al., 2002; pubmed:). [from MIM:614998; 2016.01.25]
Many to one: 2 human to 1 Drosophila. The human genes GATAD2B and GATAD2A are orthologous to the fly gene Dmel\simj.
Ortholog of human genes GATAD2B and GATAD2A (1 Drosophila to 2 human). Dmel\simj shares 30-31% identity and 42% similarity with two human genes.
