Association of SNP (rs1360780) in FKBP5 Gene and Plasma Cortisol Levels in Children with Autism Spectrum Disorder

The inconsistent results about cortisol levels in individuals with autism spectrum disorder (ASD) may be suggestive of other factors like gene polymorphisms rather than the disorder itself. We aimed to investigate the rs1360780 polymorphism in the FK506 binding protein 5 (FKBP5) gene and its relation to ASD and cortisol levels. Eighty-nine children with ASD ranging in age from two to fifteen years were selected for the study group, and eighty-six healthy children were selected for the control group. Blood samples were collected between 10 and 12 am in the morning. Enzyme linked immunosorbent assay and polymerase chain reaction were used to assay serum cortisol levels and genotyping, respectively. The mean cortisol levels for the study and the control groups were 8.5±3.6 μg/dL and 6.1±3.5 μg/dL, respectively. Cortisol levels were significantly higher in the study group compared to the control group (p<0.001). There was no statistically significant difference in terms of allele and genotype frequencies between the groups (p>0.05). Carrying the C allele was found possibly to increase the cortisol levels in the study group. This is the first clinical study to evaluate the association between rs1360780 polymorphism in the FKBP5 gene and serum cortisol levels in children with ASD compared to those of healthy participants. Since the prevalence of ASD is gradually increasing in recent years, possible endocrine and related genetic factors should be borne in mind while examining this population.