How would pharmacogenomic (pharmacogenetics and genomics) testing benefit children with psychiatric (psych) disorders?

From the Guidelines

Pharmacogenomic testing can significantly benefit children with psychiatric disorders by helping clinicians select more effective medications with fewer side effects, as it analyzes a child's genetic makeup to determine how they might metabolize and respond to specific psychiatric medications. This testing is particularly valuable for children, who are more vulnerable to medication side effects and often cannot articulate their symptoms clearly. According to a study published in the Journal of the American Academy of Child and Adolescent Psychiatry in 2020 1, there is currently no clear role for pharmacogenomic testing in medication selection, but this may change as additional evidence accumulates. However, another study published in the Mayo Clinic Proceedings in 2016 1 highlights the potential merit of developing infrastructure to individualize medicine and identify the right drug for the right patient.

The testing typically involves a simple cheek swab or blood sample, with results available within 1-2 weeks. The information remains valuable throughout the child's life as their treatment needs evolve. Pharmacogenomic testing works by identifying variations in genes that encode drug-metabolizing enzymes (like CYP2D6 and CYP2C19), drug transporters, and drug targets, allowing for truly individualized treatment rather than the traditional trial-and-error approach that can be especially challenging and potentially harmful for developing brains. For example, testing can identify if a child is a poor metabolizer of SSRIs like fluoxetine or sertraline, allowing doctors to adjust dosing or choose alternative medications.

Some key points to consider when using pharmacogenomic testing in children with psychiatric disorders include:

• The potential for genetic variation to contribute to the differential risk to benefit ratio of antidepressants, as highlighted in a study published in the Mayo Clinic Proceedings in 2016 1
• The importance of slow up-titration and close monitoring when starting or adjusting medications, particularly in younger children, as recommended in the Journal of the American Academy of Child and Adolescent Psychiatry in 2020 1
• The need for education and awareness about potential side effects, such as suicidal thinking and behavior, behavioral activation/agitation, and serotonin syndrome, as discussed in the Journal of the American Academy of Child and Adolescent Psychiatry in 2020 1
• The potential for pharmacogenomic testing to inform treatment decisions and improve outcomes in children with psychiatric disorders, as suggested in a study published in the Journal of the American Academy of Child and Adolescent Psychiatry in 2009 1.

From the Research

Benefits of Pharmacogenomic Testing for Children with Psych Disorders

• Pharmacogenomic testing can help predict treatment response, side effects, and medication selection in children with psychiatric disorders, such as attention-deficit/hyperactivity disorder (ADHD), anxiety, and depressive disorders 2.
• This type of testing can provide personalized drug metabolism profiles for psychotropic medications, which can aid in individualizing and optimizing complex medication regimens for adolescents with autism spectrum disorders 3.
• Pharmacogenetic testing can also inform dosing for antidepressants commonly used in child and adolescent psychiatry, as well as the tolerability of some psychotropic medications 4.

Potential Applications and Limitations

• Pharmacogenomic testing may have a role in predicting treatment response, side effects, and medication selection in youth with ADHD, depressive, and anxiety disorders 2.
• However, the application of pharmacogenomics to individualized/precision medicine in pediatric patients remains challenging due to numerous divergent pathways between medication/medication dose and clinical response and side effects 2.
• The implementation of pharmacogenetic testing in clinical practice still has barriers, mainly due to a lack of evidence, and more robust studies are needed to assess its potential benefits 5.

Clinical Use and Acceptability

• Both physicians and families have agreed that pharmacogenetic testing is a useful tool to improve medication selection, and it can be accepted and feasible in a child and adolescent psychiatry clinic 6.
• However, the time from sample collection to having test results and consult notes available may impair the utility of pharmacogenetic testing in clinical decision-making 6.
• Expert consensus guidelines for dosing or identifying hypersensitivity risk are available from the Clinical Pharmacogenetics Implementation Consortium (CPIC), which provides transparent, regularly updated, and evidence-based evaluations of pharmacogenetic data 4.