Using genetics to anticipate to disease

Greater understanding of the human genome has allowed researchers to determine an individual’s risk of disease based on his or her genetic traits. However, associations between individual genes and known diseases are still being discovered. A recent study published by the FASEB Journal investigated the relationship between macrophage migration inhibitory factor (MIF) gene polymorphisms and sepsis, an inflammatory bacterial infection. Prior research had shown that meningococcal sepsis was directly associated with high blood concentrations of MIFS, cytokines used to signal danger and to promote inflammation and cell proliferation. Knowing that polymorphisms of the MIF gene were also responsible for diseases like psoriasis, asthma, and cystic fibrosis; researchers sought to determine if the same polymorphisms of the gene were also responsible for the onset of sepsis. Researchers targeted their studies on a “5 to 8 CATT tetranucleotide repeat (CATT5–8)… and a G/C single-nucleotide polymorphism (SNP) at -173”.

266 patients with sepsis admitted to a London-based pediatric intensive care unit between 1992 and 2002 were screened for both polymorphisms and were examined for risk of mortality (using the Pediatric Index of Mortality). As a control group, 200 healthy Caucasians were screened for carriage of either polymorphism. The researchers determined as a result of the study that a CATT₅ microsatellite polymorphism was responsible for higher mortality rates among infants with sepsis. Interestingly, they also discovered that, among healthy individuals, MIF levels were lower in those that had the CATT₅ microsatellite polymorphism on the MIF gene. Researchers speculated in their report that this could mean that CATT₅ microsatellite polymorphisms results in individuals having an insufficient level of protection from disease typically offered by MIFs, even though higher MIF levels are typically associated with disease.

The report did note though that this finding could be confounded by both a small mortality rate among the patients screened and by the potential for other polymorphisms also being responsible for the onset of the disease. With this information, doctors are one step closer to being able to screen and pre-treat infants for sepsis through genetic examinations.