This report describes intellectual disability, X-linked 9, also referred to as intellectual developmental disorder, X-linked 9 (XLID9). This form of intellectual disability exhibits sex-linked recessive inheritance. The human gene implicated in this disease is FTSJ1, which encodes a methyltransferase that modifies nucleotides in the anticodon loop of specific tRNAs. There are two orthologous genes in Drosophila, Trm7-32 and Trm7-34; multiple genetic reagents have been generated for both fly genes, including loss-of-function mutations and RNAi-targeting constructs.
The human FTSJ1 gene has not been introduced into flies.
The two Drosophila genes, Trm7-32 and Trm7-34, divide the functions of human FTSJ1, which methylates both positions (positions 32 and 34 of the tRNA anticodon loop). To model this disease double homozygous mutant animals were used: a synaptic overgrowth phenotype is observed in the neuromuscular junctions of mutant larvae; long-term memory but not the short-term is significantly altered in mutant adults.
[updated Mar. 2023 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).
[INTELLECTUAL DEVELOPMENTAL DISORDER, X-LINKED 9; XLID9](https://omim.org/entry/309549)
[FTSJ RNA 2-PRIME-O-METHYLTRANSFERASE 1; FTSJ1](https://omim.org/entry/300499)
XLID9 patients exhibit moderate to severe intellectual disability. [from MIM:309549; 2023.03.14]
X-linked intellectual developmental disorder-9 (XLID9) is caused by mutation in the FTSJ1 gene. [from MIM:309549; 2023.03.14]
FTSJ1 encodes a methyltransferase that methylates the 2'-O-ribose of nucleotides at positions 32 and 34 of the tRNA anticodon loop of substrate tRNAs.
One to many: 1 human gene to 2 Drosophila genes.
High-scoring ortholog of human FTSJ1 (2 Drosophila to 1 human).
Moderate to high-scoring ortholog of human FTSJ1 (2 Drosophila to 1 human).
