[P2-9] Five cases of autism spectrum disorder with syntaxin1A gene haploidy
Syntaxin1A (STX1A) gene encodes a neuronal synaptic plasma membrane protein regulating the secretion of neurotransmitters and neuromodulators, and also closely related to synaptic plasticity. STX1A gene ablated mice (null and heterozygote mutants) show normal synaptic transmission via glutamate or GABA, while the secretion of monoamines or neuropeptides is reduced in those mice. STX1A gene ablated mice exhibit abnormal behavioral profiles, similar to human autism spectrum disorder (ASD) symptoms (Fujiwara et al, 2010, 2016). To determine whether copy number variation of STX1A gene correlate with ASD, we performed copy number assay using blood or saliva samples from ASD patients (based on the DSM-IV criteria). Interestingly, STX1A gene haploidy was found in 5 of 83 cases. All of gene haploidy cases showed either normal intelligence or mild intellectual disability (with the WISC). With normal intelligence or mild intellectual disability cases, STX1A gene haploidy was 6.9% (5/72). In the parents and siblings of ASD patients with gene haploidy, copy number of STX1A gene was normal. Furthermore, we assessed the clinical course including a comparison of the childhood and current states with the PARS, ADHD-RS and CGAS in 5 cases of STX1A gene haploidy. Clinical courses of 5 cases improved with growth, and their current social adaptations were mostly good. Therefore, STX1A gene haploidy was one of possible cause of ASD with normal or mild intellectual disability. We further study by increasing the number of cases. Kofuji and Akagawa will correspond to this work.