In the present study, however, we showed that AOM-3DSS-treated Clec7a−/− mice co-housed with WT mice or Clec7a−/− mice under GF conditions or ABX-treated ApcMin/+Clec7a−/− mice still developed smaller number of polyps than WT mice, indicating that commensal microbiota are not responsible for the reduced polyp formation in Clec7a−/− mice. This evidence concerns the gene CLEC7A and infectious otitis media.