Korean medical research has identified a specific gene that is associated with leukopenia ― a decrease in white blood cells ― in patients with autoimmune diseases receiving immunosuppressive treatment, Korea’s Health Ministry announced on Monday.

The research findings may help medical experts identify patients with a high risk of developing the disease prior to immunosuppressive therapy, the ministry said.

Thiopurine-induced leukopenia is one of the most dangerous side effects of immunosuppressants, drugs that weaken the body’s immune system.

The drugs are used to treat those who have received an organ transplant or suffer from autoimmune diseases such as lupus, Crohn’s disease, immune-mediated skin diseases and hair loss. However, leukopenia may lead to bleeding, life-threatening infections and even death.

The joint research team, consisting of Korean and American doctors, discovered that Crohn’s disease patients with a variation of a gene named NUDT15 have a much higher risk of developing leukopenia as a result of taking immunosupressants than those without the variation.

The team studied a total of 978 Korean patients with Crohn’s disease who were treated with immunosupressants, and those with the genetic variation in NUDT15 accounted for 19.4 percent of all patients.

While 100 percent of the patients who had two copies of the variation experienced leukopenia, more than 75 percent of those who had just one copy developed the side effect. Meanwhile, only 25.3 percent of patients without the genetic variation suffered from leukopenia.

The team also organized the same experiment with Western patients and found similar results.

According to the team, some 30 to 40 percent of Asian patients with Crohn’s disease experience leukopenia, while only 5 percent of Western patients develop the side effect.

The high chance of developing leukopenia among Asian patients has been a risk factor for Korean doctors when they treat autoimmune disease patients with immunosuppressants. They often could not use an adequate amount of the drugs since it may cause serious side effects.

“The research findings allow us to treat each patient according to their conditions,” said the research team through the Health Ministry.

“Once doctors perform a genetic test before their immunosuppressive treatment, they will be able to lower the risk of their patients developing side effects.”

By Claire Lee (dyc@heraldcorp.com)