Genetics and Autism Spectrum Disorder

The article titled “Genetics and Mitochondrial Abnormalities in Autism Spectrum Disorders: A Review” gives a detailed overview of the research that has been done on genetics in relation to ASD or Autism Spectrum Disorder over the years. In this article autism is described by “The Diagnostic and Statistical Manual of Mental Disorders IV-Text Revised” as a complex neurobehavioral disorder characterized by deficiencies in social interaction, impaired communication skills and repetitive stereotypic behavior with onset prior to three years of age. In other words, people with ASD tend to have difficulty communicating and interacting with their peers and often enjoy repeating certain functions or behaviors. It must be made clear that ASD covers a very large range of severity from functioning ASD to very sever. Trying to find the cause of ASD or Autism Spectrum disorder is difficult and includes the role of the environment, the mitochondria and genes.

This article briefly looks into the role the environment plays in stating that family and environmental studies suggest that there are genetic risk factors present in ASD. Research suggests less than twenty percent of subjects with ASD can identify the cause of their disease to be linked to one gene or genetic factor. The rest of the subjects have many genetic causes and/or environmental factors that alter gene expression without changing the DNA sequence. This is referred to as epigenetic influences. Not only does the environment play a part in ASD but biological factors such as the mitochondria play a part as well.

The mitochondria play a large role in the cause of Autism Spectrum Disorder. The Mitochondria are cellular organelles and their function is to control energy production necessary for brain activity and development. Many studies have been done on the mitochondria and how it is linked with ASD and different types of result have been produced. For example, researchers Coleman and Blass proposed that mitochondrial energy production defects could cause abnormal brain metabolism in children with autism, leading to certain biochemical levels in the body to increase; these biochemical include lactate, pyruvate and alanine. Other researchers have found that many of their subjects with ASD often times had some sort of mitochondrial defect and even more researchers are finding mitochondrial abnormalities in young children with ASD. When learning about genetics and ASD we cannot only look at the mitochondria, we have to also look at how genes are a factor in causing Autism Spectrum Disorder.

There are certain nuclear genes that have been studies and correlations have been found between the defects of these genes and ASD. One nuclear gene that has been studied in particular is DNA polymerase gamma 1. Polymerase gamma 1 or POLG1 is an important enzyme in DNA processes; if there is any kind of mutation in this gene it will impact DNA replication as well as repair. Research has found that mutations of the POLG1 gene cause deletions of DNA genes. But what do these finding have to do with ASD? Autism Spectrum Disorder is linked to defects of a specific human chromosome region. The research mentioned before found a link between genes in the nucleus specifically on the chromosome region that ASD is found on. Therefor subjects with ASD were found to be more likely to have DNA over replication and/or deletions due to mitochondrial dysfunction.

To sum up, the environmental factors have to do with ASD but these factors are a bit more difficult to pin point and study. We know the role of the mitochondria and its defects have a relation to Autism Spectrum Disorder. Several studies have linked ASD to defects in the copying of DNA and interactions with nuclear genes. By looking at all three of these factors we hope to have a better understanding of what causes Autism Spectrum Disorder.

This article was very interesting to me and I really enjoyed writing about it. I decided to write about this article because I have a young cousin who has a form of Autism. I thought it would be interesting to learn what exactly caused him to get this disease. After reading the article I did learn a lot about what factors play a part in ASD. There is so much that goes into the causation of not only ASD but other diseases as well. I do not think I really understand how complex the human body is and how one tiny error can cause all kinds of problems, but this article helped me to see that.

cite: Dhillon S, Hellings J. A., Butler M. G. "Genetics and Mitochondrial Abnormalities in Autism Spectrum Disorder: A Review" 322-332 Current Genomics 2011, Vol. 12, No. 5

Posted By: M. Castaneda