Differences in the biochemical composition of bile between CCA and patients with nonmalignant biliary disease (including various conditions such as SOD, PSC and gallstones) were distinguished between the two groups.10,11 One study examined bile from PSC (n=18) patients and from patients with CCA (n=16), but also included 11 who had other benign biliary conditions. The gene discussed is SOD1; the disease is cholangiocarcinoma.