Autism & PGx:Connecting the Dots
By Admera Health on Apr 30, 2019 2:53:00 PM
Autism Spectrum Disorder (ASD) is a developmental disorder that is characterized by difficulties with speech, non-verbal communication, repetitive behaviors, and social skills. According to the Center of Disease Control, autism affects about 1 out of 59 children in the United States today, and there are more than over 200,000 new autism cases in the US per year. Indicators of autism usually occur in children who are 2 to 3 years of age, however, in some cases, children can be diagnosed as early as 18 months. Autism is also a spectrum disorder whose symptoms can range from mild to severe, which can make it difficult to identify the right medications. 1,2
Some of the symptoms associated with autism include but are not limited to, making little or inconsistent eye contact, tending not to look or listen to an individual, having an unusual tone of voice, failing or being slow to respond to someone trying to gain attention, repetitive behavior, intense interest in certain topics, and being able to learn things in great detail. 2 There is not a specific cause of autism, however, science has concluded that it is a combination of genetic and environmental factors. Recently there have been several research studies that have shown genetic factors may be the most significant contributors to autism. 3
Since there is still so much unknown around the cause of autism, medications available today are meant to help treat the symptoms of autism rather than the disease itself. Patients can exhibit extreme symptoms of anxiety, Attention-deficit/hyperactivity disorder (ADHD), depression, and in some cases psychosis. Pharmacogenomics (PGx) combines the study of genetics with the science of drug delivery. Everyone responds differently to certain treatment options. One standard medication may work great for most patients, however, for some patients there is little to no benefit, or even worse, the drug could be harmful. These differences in response could be driven by the patient’s genetic profile. PGx testing can help provide additional information on how a patient may respond to medications based on their DNA. These insights can help provide clinical recommendations for certain medications. 4
Risperidone, 5,6 which is an antipsychotic used to treat irritability and aggression in autism patients, is primarily metabolized by an enzyme that is encoded from the CYP2D6 gene. Research has shown that CYP2D6 has a common copy number variant that results in a gene deletion or duplication. 4-6
A deletion in the CYP2D6 gene leads to the enzyme having little to no activity, and this person would be classified as a poor metabolizer. If a patient is a poor metabolizer, it means they can’t metabolize Risperidone properly, and it can possibly lead to adverse drug reactions. 4-6
A duplication in the CYP2D6 gene leads to the enzyme having increased activity. This person would be classified as a an ultra-rapid metabolizer. If a patient is an ultra-rapid metabolizer, it means they metabolize Risperidone too quickly, possibly leading to a lack of therapeutic response. 4-6
Risperidone is just one example of a psychiatric medication used to treat the symptoms of autism that is affected by genetics. There are a number of other psychiatric medications that are impacted by the variability of genes involved in metabolism, drug absorption, drug transport, drug response, etc. Pharmacogenomic testing provides healthcare practitioners with additional information on drug response based on the patient’s genetic profile. Using this additional knowledge, it is possible to provide clinical recommendations regarding medication selections, dosage, replacements, etc. that may improve the outcome for patients with autism spectrum disorder. 4
References:
1) NIMH » Autism Spectrum Disorder. Available at: https://www.nimh.nih.gov/health/topics/autism-spectrum-disorders-asd/index.shtml. (Accessed: 12th April 2019.
2) What Is Autism? | Autism Speaks. Available at: https://www.autismspeaks.org/what-autism. (Accessed: 12th April 2019.
3) Freitag, C. M. The genetics of autistic disorders and its clinical relevance: a review of the literature. Mol. Psychiatry 12, 2–22 (2007).
4) Brown, J. T., Eum, S., Cook, E. H. & Bishop, J. R. Pharmacogenomics of autism spectrum disorder. Pharmacogenomics 18, 403–414 (2017).
5) FDA & cder. HIGHLIGHTS OF PRESCRIBING INFORMATION. https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/210655s000lbl.pdf
6) Drugs@FDA: FDA Approved Drug Products. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&varApplNo=210655.
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