Gene Forms and Meningococcal Disease

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The summary below is from the full report titled "Variation within Genes Encoding Interleukin-1 and the Interleukin-1 Receptor Antagonist Influence the Severity of Meningococcal Disease." It is in the 1 April 2003 issue of Annals of Internal Medicine (volume 138, pages 534-541). The authors are R.C. Read, C. Cannings, S.C. Naylor, J.M. Timms, R. Maheswaran, R. Borrow, E.B. Kaczmarski, and G.W. Duff.

What is the problem and what is known about it so far?

Meningococci are a type of bacteria. They can cause severe infections, including bloodstream infections (sepsis) and infection of the membranes around the brain and spinal cord (meningitis). Antibiotics can fight these infections. However, even with treatment, outcomes in patients with meningococcal disease vary widely. Several factors, including genes, probably affect outcomes. For example, patients who die may have very high levels of certain proteins that promote inflammation. These proteins are called cytokines. Genes affect whether the cytokines are released. The particular forms of genes that affect cytokine release and outcomes in patients with meningococcal disease are not well studied.

Why did the researchers do this particular study?

To find out how particular forms of certain genes (interleukin-1 genes) are related to meningococcal disease.

Who was studied?

1106 patients with meningococcal infections and 839 blood donors.

How was the study done?

The researchers had stored blood samples from patients with proven meningococcal disease and from healthy people who were blood donors. They extracted genetic material (DNA) from the blood samples and looked at particular forms of interleukin-1 genes in the DNA. To see whether the gene forms affected chances of getting meningococcal infections, they compared gene forms in patients with infection with those in the healthy blood donors. To see whether gene forms affected survival, they compared gene forms in infected patients who lived with gene forms in those who died.

What did the researchers find?

The researchers found no association between particular forms of interleukin-1 genes and chances of getting meningococcal infection. However, they found that a particular form of one interleukin-1 gene was associated with higher chances of surviving meningococcal infections. The form was having a common gene form (called an allele) at a particular position (IL1B[–511]) on the DNA.

What were the limitations of the study?

The study examined only a few factors that might affect outcomes in patients with meningococcal infections. Cytokine levels were not measured. We do not know whether they were lower in infected patients who had the gene form that was associated with greater chances of survival.

What are the implications of the study?

Forms of interleukin-1 genes may be associated with greater chances of survival from meningococcal disease.