Autism: Current Gene Testing Techniques and the Future
Introduction
I was diagnosed with High Functioning Autism (aka Asperger’s) four years ago. To get this diagnosis was quite traumatic for me. First of all, there was the waiting. It took over two years from seeing my doctor, to receiving my first appointment to see a psychiatrist. Making this an agonising wait, for someone like me with autism. Then there was the diagnosis process itself. Which involved in depth interviews about my childhood and meetings with me and my close family. I found the whole process to be deeply personal, draining and difficult. Being autistic means that talking about my past and emotions is difficult enough, even with my closest family. So talking in depth with a stranger was almost intolerable. I am glad I got diagnosed, and it has helped me in the long run, but it took me a long time to get over the process. I just wished there was an easier way.
I remember at the time of my diagnosis, there was an idea that you could tell if a person is autistic by analysing brain scans. I loved this idea, and wished I could have done this instead. But of course it was not available at the time. I don’t think it will be anytime soon. But over the last few years something new has taken prevalence. This is to detect whether a person has autism/Asperger’s by looking at the genes in their DNA.
What are Genes and Gene Testing
In every cell in our bodies we have DNA. This has all the instructions needed for us to grow, function and reproduce. A short amount of our DNA (about 2%) is our genes. These genes make our characteristics (basically the way we are) and determine things such as our eye colour. These genes are passed on from our parents. Although this is greatly debated in the scientific community, there are approximately 20,000 protein coding genes in the human body.
When genetic testing is carried out, a sample is taken from the patient then sent to a lab for analysis. This is usually a blood sample, but a sample could be taken from saliva or a skin biopsy instead. The DNA sample will then be sequenced. This sequencing will either be: targeted (looking at specific genes), whole exome (looking at all the coded genes), or whole genome (which is basically all the DNA). Once this is completed, specialists (such as doctors and scientists) will analyse and interpret the DNA and give the results of the test. These results are then relayed to the patient from a person in the team or sent back to the doctor.
Depending on the depth of genetic testing, and other factors, the testing can take from a few weeks to several months.
How Gene Therapy Can Diagnose Autism
There have been a number of very recent studies looking into the genes of autistic people. These studies are looking to see if there are a specific set of genes that determine whether a person is on the autistic spectrum. It seems that the more studies that are done, the more likely it is that there are specific genes that are related to autism.
A study done in 2018 found that 99 Genes could be linked to autism. In this study the scientists looked at the exome sequences of 37,269 individuals. More information can be found at Yeager (2018).
A more recent massive study has just been completed and published in March 2019 by Grove et al. (2019). This looked at the whole genome of 18,381 Danish people with autism and 27,969 without. It not only found genes that relate to autism in general, but also found relationships between genes and specific types of autism (such as Asperger’s/high functioning, atypical or unspecified types of autism). Along with linking autism with schizophrenia and depression for some people. In addition, for some people, it found a link between one type of autism to having a higher IQ. These people tended to stay in education for longer periods (such as studying at university).
Although this research is in its infancy, genetic tests are already being taken to determine the likelihood of a person having autism or not. A close friend of mine recently had such a test. The results outlined he had ADHD and autism just from looking at his genes. He went on to have further assessments that proved this to be true.
Is Autism Hereditary
From the Danish autism study above, one of the leading scientists (Professor Mark Daly) said that autism has a heredity factor of about 80% (Neuroscience News (2019)). So it is mostly passed on from one parent or the other through their genes, but not always.
Hopes for the Future
There is a great deal of research occurring around genetics at the moment. It seems that we are just at the beginning of what can be achieved. As the years pass by hopefully, one day, genetic testing will available to everyone who is likely to be autistic. This will hopefully be able to identify, with a high degree of certainty, if a person is autistic or not and the type of autism that this person has. As this test is genetic it can be done at much earlier stage in a person’s life (maybe even before the child is born) so that help is available from a much earlier age than it is currently. It should also make the diagnosis process faster and easier than current methods. I know it is at the early stages but one day, in the far future, it could possibly be used to target treatment or prevent autism from being passed on from one generation to the next.
References
- Genetic Disorders UK (2019) Genetic Testing. https://www.geneticdisordersuk.org/aboutgeneticdisorders/genetictesting
- Grove, J. et al. (2019). Identification of common genetic risk variants for autism spectrum disorder. NATURE GENETICS. 51 (1), 431–444.
- Neuroscience News (2019). First Common Risk Genes for Autism Discovered. https://neurosciencenews.com/asd-risk-genes-10825/
- Yeager (2018) The Scientist: More Autism Genes Identified. https://www.the-scientist.com/news-opinion/more-autism-genes-identified-64957
