SPINK1 and Familial prostate cancer: Interestingly, the SPOP-mutant subtype of prostate cancer has some notable molecular features, including mutual exclusivity with ERG rearrangement, elevated levels of DNA methylation, the co-occurrence CHD1 deletions, and overexpression of SPINK1 mRNA, supporting the concept that SPOP-mutant tumors represent a distinct molecular subclass of prostate cancer [4].