4 رهل دوازدهم / شره سوم. سا ژنتیک در هزا3612 Autism which occurs before three years of age is a neurogenetic disorder with a vari- ety of impairments in social communication and speech development of the children. However, recently, it has been introduced as a multi-genetic disorder with a profound epigenetic impact on its pathology. According to recent reports, epigenetic silencing of the RORa gene (which has an essential role in neural tissue development) that oc- curs due to the methylation of its promoter region in autistic children can explain a significant portion of the molecular pathogenesis of autism. Therefore, in the current study, the accuracy of this opinion was evaluated in Iranian autistic population. The methylation status of a 136 bp sequence of a CpG island in the promoter regions of the RORa gene (from -64 to -200) which encompasses 13 CpG sites was examined in lym- phoma cells of 30 children with autism (autistic individuals, monozygotic and dizygot- ic twins) and compared with normal children after sodium bisulfite treatment through the Melting Curve Analysis-methylation assay (MCA-Meth). Also, qRT-PCR analysis was used for the evaluation of mRNA transcripts of the RORa gene and confirmation of the MCA-Meth analysis. In this study, no amount of methylation was found in the evalu- ated promoter regions of healthy and unhealthy children and melting curves of all studied cases matched perfectly with unmethylated melting curves of the controls. Also, qRT-PCR analysis completely confirmed the results of MCA-Meth analysis. Meth- ylation of the RORa promoter regions cannot be considered a general epigenetic risk factor in all geographic areas and probably does not respond any significant questions about the molecular pathogenesis of autism, at least in the autistic population of Iran. Key words: Autistic Disorder; Methylation; Epigenomics; CpG islands Promoter Regions RORa Gene Contribution to Autism; Another Epigenetic Layer on Autism Complexity Seyyed Mohammad Mousavi, Mohammad Kazemi,Mansour Salehi, Elahe Kamali, Padideh Karimi, Mojgan Karahmadi. ABSTRACT Mojgan Karahmadi, MD Assistant Professor, Psychiatry Department, School of Medicine, Isfahan University of Medical Sciences, Isfahan, IR Email: karahmadi@med.mui.ac.ir Submission Date: 13. Sep. 2014 Acceptance Date: 15. Nov. 2014 * *