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Psychiatry Investig. 2014 Oct;11(4):476-80. doi: 10.4306/pi.2014.11.4.476. Epub 2014 Oct 20.

Association of SNAP-25 Gene Ddel and Mnll Polymorphisms with Adult Attention Deficit Hyperactivity Disorder.

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Department of Psychiatry, School of Medicine, Pamukkale University, Denizli, Turkey.
Department of Medical Biology and Genetics, School of Medicine, Mersin University, Mersin, Turkey.
Department of Childhood and Adolescent Psychiatry, School of Medicine, Pamukkale University, Denizli, Turkey.
Department of Psychiatry, Servergazi State Hospital, Denizli, Turkey.
School of Health, Muğla University, Muğla, Turkey.



The synaptosomal-associated protein of 25 kDa (SNAP-25) gene is a presynaptic plasma membrane protein and an integral component of the vesicle docking and fusion machinery mediating secretion of neurotransmitters. Previously, several studies reported association between SNAP-25 and attention deficit hyperactivity disorder (ADHD). We investigated whether these SNAP-25 polymorphisms (MnlI T/G and DdelI T/C) were also associated with ADHD in the Turkish population.


Our study comprised unrelated 139 subjects who met DSM-IV criteria for ADHD and 73 controls and all were of Turkish origin. Genetic analyses were performed and patients were evaluated with Wender-Utah Rating Scale and Adult ADD/ADHD DSM IV-Based Diagnostic Screening and Rating Scale.


SNAP-25 DdelI polymorphism was not associated with ADHD but there was a statistically significant difference between ADHD patients and controls for SNAP-25 MnlI polymorphism. For SNAP-25 MnlI polymorphism patients with G/G genotype of the SNAP-25 gene MnlI polymorphism had higher Wender-Utah scores and higher scores in the 1st and 3rd parts of adult ADD/ADHD Scale.


We detected a significant association of the MnlI polymorphism in our ADHD sample which was similar to previous findings. Our study also revealed that SNAP-25 MnlI polymorphism was also associated with symptom severity of ADHD. This study is also, the first report on the association of SNAP-25 with ADHD in the Turkish population.


ADHD; Genetic; SNAP-25 gene

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