RT Journal Article SR Electronic T1 Dosing azathioprine in thiopurine S-methyltransferase deficient inflammatory bowel disease patients JF Gut JO Gut FD BMJ Publishing Group Ltd and British Society of Gastroenterology SP 872 OP 872 DO 10.1136/gut.2007.145912 VO 57 IS 6 A1 L J J Derijks A1 R B van Helden A1 D W Hommes A1 P C Stokkers YR 2008 UL http://gut.bmj.com/content/57/6/872.1.abstract AB