New substitutions of mitochondrial DNA in Iranian autistic children

Abstract

Introduction: Autism spectrum disorders (ASDs) are neurodevelopmentally complex diseases with causative de-novo and inherited genetic factors. They contain a range of cognitive and behavioral conditions such as Asperger's syndrome, pervasive developmental disorder and autism. Our study subjects were children with autistic behaviors (15-60 CARS Score). Material and methods: The DNA extraction process was done using a GeNet Bio DNA extraction kit, and the region of interest was amplified using independent PCR runs. After purification of PCR products, both strands were sequenced by the Big Dye Termination system. The automated sequencing on an ABI 3700 was directly determined with a capillary sequencer machine. Both primers' sequencing results were analyzed using a bioinformatics tool, Sequencher Software 5. Results: In the population we studied, the variant G9055A (located at ATP6) was reported to be pathogenic (CAAD > 20 and PolyPhen shows it to be probably damaging). In this variant amino acid alanine converts to threonine. A to T substitutions induce accumulation of amyloid fibril in the brain because threonine prefers to form a β sheet as a necessary stage in the amyloidogenic process. Conclusions: In our study of patients with autism, we found one case having an interesting association with amyloidosis. It is hoped that by finding such markers, the children will be treated with more certainty.