NRAS and colorectal cancer: Studies of Egyptian [99] and Chinese [100] colorectal cancer patients with schistosome infection found an association of KRAS mutation with schistosome infection, and while a study of bladder cancer patients with schistosome infection did not find an increased frequency of mutation in NRAS or KRAS, it found an unusually high frequency of a mutation in codon 13 of HRAS, another member of the RAS family [101,102].