Aim of the study:
Autism spectrum disorder (ASD) is a neurodevelopmental condition considered by early-onset difficulties in social communication. Insulin-like growth factors (IGFs) play crucial roles in synapse formation. Most of circulating IGFs are bound to IGF-binding proteins (IGFBPs) that modify IGF action. IGFBPs prolong the plasma half-life of IGFs. In this project we studied the association of IGF1/2 and IGFBP1-6 serum concentration with the severity of ASD (Levels 1-3; Mild, Moderate and severe, respectively).

Subject or material and methods:
A hundred and eighty patients with ASD (Mild; n=69, Moderate; n=58 and Severe; n=53) and 118 controls age matched were used in this project and IGF1/2 and IGFBP1-6 serum concentration were measured by ELISA.

Results:
The results demonstrated that IGF1, IGF2 and IGFBP1-6 were present in all serum samples. The results showed that the concentration of IGF1 and IGF2 was significantly higher in ASD patients when compared to controls, starting from stages I to III ASD, a significant increase of IGF1 and IGF2 serum concentration was observed. Results obtained also showed that IGFBP1-6 concentration in the ASD group were lower when compared to controls and low serum IGFBP1-6 concentration is associated with advanced stages of ASD.

Discussion:
IGFs plays important role in synapse formation and changes in IGFs expression may be important in the pathogenesis of ASD.

Conclusions:
It is suggested that IGFs and IGFBPs may be involved in the pathogenesis of ASD. Therefore, the detection of serum soluble IGFs and IGFBPs may be useful in classifying ASD.