By identifying the presence of the gene variations in HLA-B*1502 and HLA-A*3101, the GeneSight^® Psychotropic pharmacogenomic test can predict if a patient may be at an increased risk of severe skin reactions, such as Stevens-Johnson Syndrome (SJS), when taking certain mood stabilizers. SJS is a rare, serious disorder of skin and mucous membranes, usually caused by a reaction to a medication.

The human leukocyte antigen (HLA) complex plays an important role in immune regulation. HLA-B*1502 can predict an increased risk of severe skin reactions, including SJS, when taking certain mood stabilizers – specifically carbamazepine, oxcarbazepine, lamotrigine, and phenytoin. HLA-A*3101 can predict severe skin reactions with carbamazepine.

Clinicians should use extreme caution when using these medications for patients that test positive for the HLA-B*1502 or HLA-A*3101 alleles.

In 2007, the FDA issued a warning about carbamazepine’s involvement in SJS in genetically at-risk patients. The most current warning from 2018 notes that the frequency of the HLA-B*1502 allele is highest in certain Asian populations, with the highest prevalence being reported in Hong Kong, Thailand, Malaysia, and the Philippines. Genetic testing may be beneficial for these patients. The FDA-approved package insert for carbamazepine recommends testing for HLA-B*1502 in patients of Asian descent prior to starting carbamazepine. However, the label also states that the difficulty in determining ethnic ancestry and the likelihood of mixed ancestry should also be considered.

SJS requires immediate medical attention. Symptoms include body aches and flu-like symptoms of fever, fatigue, and cough. These signs are typically followed by unexplained widespread skin pain, a red or purple skin rash that spreads, and blisters on your skin and the mucous membranes of your mouth, nose, eyes and genitals. If you experience any signs and symptoms of this condition, seek emergency medical help. If you believe this may be a reaction to a medication, be sure to tell your healthcare provider right away.

For more information on the GeneSight test, visit genesight.com, email us at medinfo@myriad.com, or phone 855.891.9415.

This document is for educational purposes related to pharmacogenomics and personalized medicine only and should not be considered medical advice. The information is based on scientific opinion from industry experts and is intended to provide additional information to healthcare providers. These materials may be changed, improved, or updated without notice. Myriad Neuroscience is not responsible for any errors or omissions contained in third party content. We encourage you to contact us for specific scientific advice regarding our GeneSight® tests. You may print a copy of this document for your own personal noncommercial use. You may not copy any part of this document for any other purpose, and you may not modify any part of this document without the permission of Myriad Neuroscience. “GeneSight,” “Myriad Neuroscience” and associated logos are registered trademarks of Myriad Neuroscience. © 2020 Myriad Neuroscience. All rights reserved.