Genetic Variants Linked to Skin Reactions to Phenytoin
Several key genetic variants, including one that is known to reduce drug clearance, have shown a strong association with skin reactions while using the antiepileptic drug known as phenytoin.
About the Skin Reaction Risk
According to Medscape Medical News, phenytoin is valued highly as a frontline antiepileptic drug.
However, it can cause adverse reactions to the skin ranging from mild rashes to more severe and possibly life threatening reactions.
Severe reactions are less common, but with the cases of Steven-Johnson Syndrome and toxic epidermal necrolysis (TEN) mortality rates are often high at 10 to 50 percent.
Details of the Phenytoin Study
According to Medscape Medical News, Chang Gung Memorial Hospital in Keelung, Taiwan, conducted a genome-wide association study. There were samples taken from 60 patients with phenytoin related skin reactions.
They found that the variants of gene type CYP2C, including CYP2C9*3, were directly associated with the phenytoin related skin reactions.
This gene type was associated with 11 times higher odds of attaining the reaction.
Patients who developed the skin reactions but didn’t have the gene type CYP2C, were found to have delayed clearance. This suggested that non-genetic factors could cause adverse skin reactions.
Non-genetic factors such as renal insufficiency, hepatic dysfunction, and the use of substances that compete or inhibit the enzymes may cause skin reactions as was reported by Science Daily.