Genetics and Immunity: Same Infection, Different Illness

By Ursula Biba

Researchers at The Rockefeller University have found a biological mechanism that elucidates why certain individuals are more deleteriously affected by common bacterial infections than others. Dr. Casanova, of the St. Giles Laboratory and Howard Hughes Medical Institute, and team did so by studying the case of a young girl who developed a life- threatening infection from the extremely common Staphylococcus aureus bacterium. Scientists had thought they found the answer they were looking for after analyzing her genome and finding a single letter substitution in a gene that codes for TIRAP, which is active in the immune response. However, study of the case’s family revealed they all shared that point mutation— but no one else got dangerously ill. As TIRAP is integral to immune system’s first line of defense using specific cells and recognition mechanisms that develop before birth, researchers found the true culprit of the disease in the secondary immune response. The young patient’s family did not exhibit the same pathology because they acquired the antibodies necessary to fight off the bacterial infection from their environment. These antibodies target LTA found on the surface of the staph bacterium. The patient’s family members’ acquisition of this antibody restored immune cell function and compensated for the genetic mutation. Not only does this reveal how two individuals with almost the same DNA can get two different infections, but that these findings can be applied to explain other similar infections.


Rockefeller University. (2017, February 23). Why a common bacterium can produce severe illness. ScienceDaily. Retrieved March 4, 2017 from