A particular allele of the IL-8 gene may be a determining factor for the severity of bronchiolitis among children. Most children are infected by the respiratory syncytial virus (RSV) that causes bronchiolitis by the age of two. For most bronchiolitis remains a mild illness but for some it can cause severe breathing problems and may require admission to hospital. The walls of airways infected with RSV have high levels of interleukin 8 (IL-8), a neutrophil chemoattractant which causes inflammation.

In research published in the December Thorax (Thorax 2000 55:1023-1027), Jeremy Hull and co-workers at the John Radcliffe Hospital in Oxford, found a single nucleotide polymorphism (allele frequency 0.44) 251 base pairs upstream of the IL-8 transcription start site. The team took DNA swabs from the mouths of 117 families whose children had been admitted to hospital with severe bronchiolitis. They found that the frequency of this allele was...