Discovery of Novel Screening Test That Can Identify Patients at Risk of Life-Threatening Side Effect with Certain Anticonvulsant Medications

SAN DIEGO, March 23, 2017 /PRNewswire/ -- A new genetic test has been discovered that allows for fast and accurate identification of individuals who carry HLA-B*15:02 and who are therefore at risk for a rare yet potentially deadly side effect of certain medications used to treat seizures and bipolar disorder.  The gene HLA-B*15:02 is strongly associated with life-threatening severe skin hypersensitivity reactions such as Stevens-Johnson syndrome and toxic epidermal necrolysis in patients treated with carbamazepine and related medications such as lamotrigine and phenytoin.

The new genetic test is based on a tagging SNP (a genetic variation) which is able to detect HLA-B*15:02 in 100% of patients who have the genetic marker, in a study of nearly 30,000 individuals from the US population. "It is very important to know whether certain patients carry HLA-B*15:02 since the side effects of some medications can be extremely serious. Currently available testing methods are limited by a variety of factors including access, availability, and accuracy," said Tanya Moreno, PhD, vice president of genetics research and development, CogenDx.  

Current FDA-approved prescribing information recommends HLA-B*15:02 screening only for patients of Asian ancestry prior to carbamazepine use, since this allele is known to be present at a higher frequency in Asian populations. Similarly, insurance coverage for HLA-B*15:02 testing prior to Carbamazepine therapy has been limited to those with Asian and Oceanian ancestry.

In a study accompanying the discovery, scientists at CogenDx discovered that HLA-B*15:02 may be present in more Americans than expected. The study identified 149 HLA-B*15:02-positive individuals, of which a subgroup of 62 had physician-reported ethnicity information.  Out of the 62 individuals with reported ethnicity, 43% were identified by their physicians as having Asian ancestry, but more than half of the remaining patients who had HLA-B*15:02 (57%) were identified as having Caucasian, African American, Hispanic, or other ethnicity.

"Our critical finding in the ethnically diverse US population is that people who may not be identified as having Asian ancestry may indeed carry HLA-B*15:02 and therefore be at risk for severe side effects. This shows that physicians may need a better indicator than self-reported ethnicity to identify which patients may be at risk." said Tanya Moreno. "We demonstrate with this study that the tagging SNP is an accurate screening tool for HLA-B*15:02 regardless of observed or self-reported ethnicity."

About CogenDx
CogenDx, the genetics brand of Millennium Health, LLC, helps clinicians personalize treatment decisions for patients using state-of-the-art molecular diagnostic technology. Our portfolio includes genetic testing that predicts response to commonly prescribed medications and determines genetic risks underlying potential surgical complications. For more information, email [email protected].

SOURCE CogenDx