Fecal microbiota diversity in survivors of adolescent/young adult Hodgkin lymphoma: a study of twins

Background: Adolescent/young adult Hodgkin lymphoma (AYAHL) survivors report fewer exposures to infections during childhood compared with controls, and they have functional lymphocyte aberrations. The gut microbiota plays a central role in immunity. Methods: We investigated whether fecal microbial diversity differed between 13 AYAHL survivors and their unaffected co-twin controls. Pyrosequencing of fecal bacterial 16S rRNA amplicons yielded 252 943 edited reads that were assigned to species-level operational taxonomic units (OTUs) and standardised for sequencing depth by random sampling. Microbial diversity was compared within vs between twin pairs and by case-control status. Results: The number of unique OTUs was more similar within twin pairs compared with randomly paired participants (P = 0.0004). The AYAHL cases had fewer unique OTUs compared with their co-twin controls (338 vs 369, P = 0.015); this difference was not significant (169 vs 183, P = 0.10) when restricted to abundant OTUs. Conclusion: In this small study, AYAHL survivors appear to have a deficit of rare gut microbes. Further work is needed to determine if reduced microbial diversity is a consequence of the disease, its treatment, or a particularly hygienic environment.