Objective To assess whether FUT2 (secretor) genotype affects disease severity and airway infection in patients with non-cystic fibrosis bronchiectasis.

Participants Induced sputum samples were obtained from 112 adult patients with high-resolution CT scan-proven bronchiectasis and at least two exacerbations in the previous year, as part of an unrelated randomised control trial.

Outcome measures Presence of null FUT2 polymorphisms were determined by gene sequencing and verified by endobronchial biopsy histochemical staining. Outcome measures were FEV₁% predicted, exacerbation frequency, and bacterial, fungal and viral components of the microbiota (measured by culture independent approaches).

Results Patients were grouped by FUT2 loss-of-function genotype; categorised as non-secretors (n=27, sese), heterozygous secretors (n=54, Sese) or homozygous secretors (n=31, SeSe). FEV₁% was significantly lower in SeSe patients compared with sese patients (mean 61.6 (SD 20.0) vs 74.5 (18.0); p=0.023). Exacerbation frequency was significantly higher in SeSe (mean count 5.77) compared with sese (4.07; p=0.004) and Sese (4.63; p=0.026) genotypes. The time until first exacerbation was significantly shorter in SeSe compared with Sese (HR=0.571 (95% CI 0.343 to 0.950); p=0.031), with a similar trend for sese patients (HR=0.577 (0.311 to 1.07); p=0.081). sese had a significantly reduced frequency of Pseudomonas aeruginosa-dominated airway infection (8.7%) compared with Sese (31%; p=0.042) and SeSe (36%; p=0.035). In contrast, fungal, viral and non-dominant bacterial components of the microbiome were not significantly different between FUT2 genotypes.

Conclusions FUT2 genotype in patients with non-cystic fibrosis bronchiectasis was significantly associated with disease outcomes, with homozygous secretors exhibiting lower lung function, higher exacerbation number and a higher frequency of P. aeruginosa-dominated infection.

Trial registration number ACTRN12609000578202 (anzctr.org.au); Pre-results.