Hunner-type IC/BPS is seen in 5–10% of cases and the analysis of their bladder wall biopsy is generally associated with high expression of T and B cell markers18, low expression of urothelial markers, high density of mast cells, focal lymphoid aggregates, overexpression of IL-6, IL-10, IL-17A, and inducible NOS (iNOS) mRNA14. This evidence concerns the gene NOS2 and Bartsocas-Papas syndrome 1.