Stx1a, also known as Shiga Toxin Type 1a, is a potent bacterial toxin. It is found in Shigella dysenteriae 1 and some serogroups of Escherichia coli. Stx1a consists of an A subunit that halts protein synthesis in target cells by injuring the eukaryotic ribosome, and a B pentamer that binds to the cellular receptor globotriaosylceramide, Gb3, mainly on endothelial cells. The toxin traffics in a retrograde manner within the cell [3].

Heterozygous and homozygous variants in STX1A can cause a neurodevelopmental disorder with or without epilepsy. Missense variants in STX1A are mainly associated with epilepsy, while inframe deletions lead to intellectual disability and autistic behavior. In silico modeling shows different impaired protein-protein interactions for these variants, suggesting two different pathogenic mechanisms [1]. A case-control study in the Chinese Han population found that STX1A gene variations contribute to the susceptibility of children attention-deficit/hyperactivity disorder (ADHD). Specific single nucleotide polymorphisms (SNPs) of STX1A were associated with ADHD and its clinical characteristics [2]. In addition, STX1A has been associated with Asperger syndrome, with certain SNPs showing a significant association [4].

In conclusion, Stx1a, as a bacterial toxin, has a well-defined structure and function related to its role in bacterial pathogenesis. In the context of human health, genetic variations in STX1A are associated with neurodevelopmental disorders such as epilepsy, intellectual disability, autism-related behaviors, ADHD, and Asperger syndrome. These associations help in understanding the role of STX1A in normal neurodevelopment and the pathogenesis of these disorders.