Gene Mutation FUT2 Influential in Non-Cystic Fibrosis Bronchiectasis

Gene Mutation FUT2 Influential in Non-Cystic Fibrosis Bronchiectasis

Patients with non-cystic fibrosis bronchiectasis have better outcomes when they have particular mutations in both copies of the FUT2 gene, according to researchers at the South Australian Health and Medical Research Institute.”

The study, “FUT2 genotype influences lung function, exacerbation frequency and airway microbiota in non-CF bronchiectasis,” was published in the journal Thorax.

Patients with non-cystic fibrosis bronchiectasis are characterized by irreversible dilation of the bronchi and persistent bacterial infections. Although it is difficult to predict how the disease will progress in individual patients, the composition of the airway microbiota may correlate with disease severity.

Mutations in the FUT2 gene result in the inability to express certain glycans in the mucosal surfaces, which are required for both beneficial and pathogenic microbes to adhere.  Researchers hypothesized that the FUT2 genotype in non-cystic fibrosis bronchiectasis patients could explain the variation in infection type, and so, the disease severity.

In the study, researchers examined 112 patients with non-cystic fibrosis bronchiectasis, of whom 24% had a specific mutation in both copies of the FUT2 gene (non-secretors), 28% had functional copies of the FUT2 gene (secretors), and 48% had one bad copy and one good copy of the FUT2 gene — called heterozygous secretors.

The research team, led by molecular microbiologist and microbial ecologist Geraint B. Rogers, found that secretors had a significantly lower lung function than non-secretors, as assessed by the forced expiratory volume in one second (FEV1). Exacerbation frequency was also found to be significantly higher in secretors than in non-secretors or heterozygous secretors.

Researchers also showed that secretors had a significantly shorter time until first exacerbation (flareup), compared to heterozygous secretors. A similar trend was observed in non-secretors, although the results were not statistically significant.

The frequency of Pseudomonas aeruginosa bacteria infections, which is associated with an accelerated decline in lung function but not fungal or viral infections, also correlated with FUT2 genotype. In fact, non-secretors had reduced frequency of P. aeruginosa-associated airway infection compared to both secretors and heterozygous secretors.

Although the precise mechanism through which secretor status affects infection and disease susceptibility is not fully understood, researchers suggested that secretor status may modify the composition of the gut microbiome (populations of bacteria in the gut), which is shown to influence host immunity, or increase the susceptibility to viral infections — which leads to increased frequency of pulmonary exacerbations.

Still, the FUT2 genotype may be a future prognostic marker that may help predicting the risk and frequency of respiratory events, such as pulmonary exacerbations, which may improve patient management.