December 31, 2013
A group of researchers have identified a genetic marker that can predict which patients infected with the new influenza A(H7N9) strain will experience more severe disease, according to data published in Proceedings of the National Academy of Sciences.
Influenza A(H7N9) has infected 134 people in nine provinces in China and caused 44 deaths, according to the paper, which was published online Dec. 23. According to WHO, there is no evidence of sustained human-to-human transmission.
“By using genetic markers in blood and lung samples, we have discovered that there are certain indicators that signal increased susceptibility to this influenza,” Katherine Kedzierska, PhD, associate professor in the department of microbiology and immunology at the University of Melbourne in Australia, said in a press release. “Higher than normal levels of cytokines, driven by a genetic variant of a protein called IFITM3, tells us that the severe disease is likely.”
Lower levels of plasma inflammatory cytokines at hospital admission were associated with faster recovery among 18 patients admitted to the hospital with H7N9, but high concentrations of interleukin-6, IL-8 and macrophage inflammatory protein-1 beta were associated with less favorable or fatal outcomes, the researchers wrote.
When they analyzed bronchoalveolar lavage samples, they found up to 1,000-fold greater cytokine and chemokine levels relative to plasma samples. They also found that patients with the rs12252-C/C genotype of IFITM3 had more rapid disease progression and were more likely to die than patients with the rs12252-T/T or rs12252-T/C genotypes.
“We call this a Cytokine Storm and people with the genetic variant of the protein IFITM3 are more likely to succumb to severe influenza infection,” Kedzierska said. “Being able to predict which patients will be more susceptible to the emerging influenza strain will allow clinicians to better manage an early intervention strategy.”
Disclosure: Kedzierska and colleagues report no relevant disclosures.