Analysis of Insulin-like growth factor-1 serum levels and promoter (rs12579108) polymorphism in the children with autism spectrum disorders

Autism spectrum disorder (ASD) is a set of neurodevelopmental disorders characterized by a deficit in social behaviors and nonverbal interactions such as reduced eye contact and facial expression. Changes in growth factors expression including Insulin-like growth factors (IGFs) have been shown in ASD. This project aimed to study the association of IGF-1 (rs12579108) promoter polymorphism and its serum concentration with ASD.DNA was extracted from blood samples of 200 ASD children and 198 healthy controls and genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and IGF-1 serum concentration was measured by ELISA.The results showed that the prevalence of AA, CA, and CC genotypes were 2%, 61%, 37% in controls and 4%, 31%, and 65% in ASD patients, respectively (P = 0.0005). The prevalence of A and C alleles in the controls were 33% and 67% and in ASD patients were 19% and 81%, respectively (P = 0.001). We have also showed that serum IGF-1 concentration in ASD and control groups was 31.45 ± 9.84 and 54.62 ± 11.63 ng/ml, respectively (P = 0.001). Our results also showed that AA genotype is significantly related to decreased serum IGF-1 concentrations in ASD (CC, CA and AA serum levels were 50.22 ± 12.68, 33.55 ± 9.13 and 22.55 ± 7.26 and in controls were 77.88 ± 17.14, 54.77 ± 15.31 and 31.33 ± 9.91 ng/ml, respectively).It is concluded that there is a significant association between IGF-1 (rs12579108) promoter polymorphism and its serum concentration with ASD. We also suggest that AA genotype is linked to lower IGF-1 serum levels and may play as risk factor for ASD.