We discovered that the expression of YKL40 was significantly increased in AR+ve PCa cell lines as they progressed towards a castrate-resistant and metastatic phenotype when compared with AR−ve PCa and normal prostate epithelial cells, suggesting that YKL40 may be regulated in an androgen-dependent manner in the PCa cell setting. The gene discussed is CHI3L1; the disease is posterior cortical atrophy.