Chi3l1 is expressed in the detrusor mast cell granules and submucosal macrophages of BPS/IC patients and is associated with detrusor fibrosis, indicating that the serum and urine levels of Chi3l1 can serve as valuable biomarkers for evaluating bladder fibrogenesis in this disease [217]. Here, CHI3L1 is linked to Bartsocas-Papas syndrome 1.