Evaluation of the relationship between anti-gad antibody and biochemical parameters and autism symptoms in children with autism spectrum disorder; Case-control study

Objective: The aim of this study was to measure Anti-Glutamic Acid Decarboxylase (GAD) antibody, Anti-Streptolysin O (ASO), and biochemical parameters (ferritin, iron, vitamin D, vitamin B12, TSH) in patients diagnosed with Autism Spectrum Disorder (ASD) and healthy children and in patients with and without regressive ASD, and to investigate the relationship between laboratory data and clinical signs of autism. Material and Method: This study was planned as a prospective controlled study. The study included patients aged 2-8 years who were diagnosed with Autism Spectrum Disorder according to DSM-V and applied to Çukurova University Faculty of Medicine Child and Adolescent Psychiatry Outpatient Clinic. Healthy children of similar age and gender were included in the control group. All subjects participating in the study had their Anti-GAD antibody, ASO, serum iron, ferritin, vitamin D, vitamin B12, TSH, and folate levels checked. The Autism Behavior Checklist (ABC), Modified Early Childhood Autism Screening Scale (M-CHAT), and AGTE were applied to the autism spectrum disorder group. Children with ASD were classified as regressive autistic and non-autistic by clinical evaluation. The data of children with ASD were compared both within themselves and with healthy children. Results: The mean age of the ASD group was 48.3±20.1 months, and the mean age of the children in the control group was 54.6±19.4 months. Anti-GAD antibody levels were significantly higher in children with ASD compared to healthy children (p:0.003). In the "Sensory Skills" sub-score of the ABC test, the scores of girls with ASD were statistically significantly higher than boys (p:0.013). While 37.7% (n=17) of children with ASD did not have autistic regression, 62.3% (n=28) had autistic regression. Anti-GAD antibody levels, serum iron, ferritin levels, and ABC total scores were significantly higher in children with regression than children with ASD who did not show regression (respectively p:0.020, p:0.03, p:0.04, p:0.04, respectively). A statistically significant positive correlation was found between anti-GAD titration and ABC total score (r:0.724, p:0.01). A statistically significant negative correlation was found between anti-GAD titration and vitamin D (r:-0.360, p:0.015). A statistically significant negative correlation was found between ABC score and vitamin D (r:-0.297, p:0.047). Conclusion: The data from this study suggests that Anti-GAD antibody may be associated with the etiopathogenesis of ASD, the severity of clinical symptoms of ASD, and the autistic regression seen in children with ASD. Further studies on larger clinical samples are needed to use Anti-GAD antibody as a biomarker in the etiopathogenesis, diagnosis, and clinical course of autism. Key Words: Autism, Anti-Glutamic Acid Decarboxylase Antibody, Autistic Regression, Anti-Streptolysin O Antibody