Scientists have identified a gene mutation that can cause fatal illnesses in children.

The new genetic immunodeficiency is the result of a mutation in a gene called STAT2. The mutation causes patients to be extremely vulnerable to normally mild childhood illnesses, including rotavirus and enterovirus. In the past patients with “hidden” immunodeficiencies—defects that were not obvious from the outset—often became extremely ill or died before their genetic disorders were diagnosed.

However, due to advancements in technologies and tools, researchers are now able to identify extremely subtle defects of the human immune system This allows clinicians to provide children with the proper therapies before illnesses prove fatal.

Adrian Liston, Ph.D., a professor at VIB-KU Leuven in Belgium, was able to identify a gene mutation causing immunodeficiency that can be fatal during childhood, enabling children to be diagnosed, monitored and preemptively treated for the disorder.

“I wouldn’t be surprised if, when we finally do complete the identification of all genetic immunodeficiencies, we discover that up to one in 100 children are affected,” Liston said in a statement. “The ‘hidden’ ones are especially insidious because they do not present as obviously as other genetic immune disorders.

“In our study, one of the patients did unfortunately die before a diagnosis could be made,” he added. “The other patient is alive and well and now that she has been diagnosed, she is being carefully watched. We can do something about most immunodeficiencies—if only we can identify them.”

Immunodeficiencies, which are more common than previously thought, can cause a variety of disorders ranging from the well-known “bubble boy” to the nearly impossible to detect hidden defects.

Isabelle Meyts, a professor with UZ Leuven in Belgium and KU Leuven explained the importance of assessing the severity of childhood illnesses.

“When an otherwise healthy child experiences extremely severe infection with a common pathogen, like influenza or the chickenpox virus, or whenever a child is particularly vulnerable to infection with a single pathogen, an underlying defect in the immune system is likely,” Meyts said in a statement. “Likewise, a family history of a child succumbing to infection should alert the family and the clinician.

“Identifying the causative gene defect allows for genetic counseling of the family and for preventive measures to be taken.”

Liston’s lab is working to develop a unique system that can detect defects and inflammatory diseases, leading to new treatments that can be administered.

“We seek to identify every possible cause of genetic immunodeficiency so that every child displaying warning signs can be tested and treated before it is too late,” Liston said.

The study was published in The Journal of Allergy and Clinical Immunology