The 16p11.2 deletion is a recurrent CNV (copy-number variant) extending approximately 593kb, a region that includes 25 unique genes. It is associated with a range of neurodevelopmental features, including autism, intellectual disability, epilepsy, and obesity. The variability of associated phenotypes and other findings suggest that the observed phenotypes in 16p11.2 deletion are not caused by haploinsufficiency of a single causative gene, but rather are caused by multiple dosage-sensitive genes in the region, which may also interact with each other.
Of the 25 human genes within the 16p11.2 deletion, fly orthologs of 14 were identified. Using RNAi-effected knockdown targeted at each fly gene, multiple cellular and neurodevelopmental phenotypes were assessed. Those with significant neurodevelopmental phenotypes include rl (orthologous to MAPK3; see FBhh0000842), Pp4-19C (orthologous to PPP4C), CG10465 (orthologous to KCTD13), Ald1 (orthologous to ALDOA), Tao (orthologous to TAOK2; see FBhh0001219), and Rph (orthologous to DOC2A). Phenotypes of pairwise knockdowns were assessed in the developing eye; interactions with other neurodevelopmental genes were also assessed in the developing eye. In a separate study, neurodevelopmental phenotypes at the larval neuromuscular junction are described for two fly kinesin genes, Klp68D and Klp64D; KIF22, one of many kinesin genes in human, is within the 16p11.2 deletion.
Results support a complex interaction model for disease pathogenicity, where multiple 16p11.2 genes are sensitive to dosage imbalance and participate in complex interactions; they both enhance and suppress the phenotypic effects of each other; they are also modulated by other genes in the genetic background.
[updated Apr. 2021 by FlyBase; FBrf0222196]
[CHROMOSOME 16p11.2 DELETION SYNDROME, 593-KB](https://omim.org/entry/611913)
[CHROMOSOME 16p11.2 DELETION SYNDROME, 593-KB](https://omim.org/entry/611913)
The 16p11.2 recurrent microdeletion phenotype is characterized by developmental delay, intellectual disability, and/or autism spectrum disorder. Seizures are observed in approximately 20% of individuals; macrocephaly, seizures, and/or obesity are also observed in some individuals. [Gene Reviews, 16p11.2 Recurrent Microdeletion; 2019.06.28]
Chromosome 16p11.2 deletion syndrome is associated with a range of neurodevelopmental features, including autism and severe early-onset obesity. [from MIM:611913; 2019.06.28]
Both microdeletions and microduplications can result from recurrent CNVs (copy-number variants). Recurrent CNVs generally arise by nonallelic homologous recombination during meiosis, with breakpoints in the large duplicated blocks of sequence flanking the CNV event. Because the breakpoints cluster within defined regions, the extent of recurrent CNVs is essentially identical even in unrelated individuals (Watson et al., 2014; pubmed:24773319).
High-scoring ortholog of human MAPK1 and MAPK3 (1 Drosophila to 2 human). Dmel\rl shares 76-82% identity and 84-90% similarity with the human genes.
High-scoring ortholog of human PPP4C (1 Drosophila to 1 human); multiple other homologous genes in both species. Dmel\Pp4-19C shares 91% identity and 96% similarity with the human gene.
High-scoring ortholog of human KCTD10, KCTD13, TNFAIP1 (1 Drosophila to 3 human). Dmel\CG10465 shares 57-68% identity and 71-79% similarity with the human genes.
High-scoring ortholog of human TAOK1, TAOK2, TAOK3 (1 Drosophila to 3 human). Dmel\Tao shares 47-49% identity and 60-64% similarity with the human genes.