Assessment of thiopurine S-methyltransferase activity in patients prescribed thiopurines: A systematic review

Annals of Internal Medicine

Volumn 154, Issue 12, 2011, Pages 814-824

  Booth, Ronald A ^a   Ansari, Mohammed T ^b   Loit, Evelin ^b   Tricco, Andrea C ^c   Weeks, Laura ^b   Doucette, Steve ^d   Skidmore, Becky ^e   Sears, Margaret ^e   Sy, Richmond ^a   Karsh, Jacob ^e  

^a UNIVERSITY OF OTTAWA   (Canada)

^b UNIVERSITY OF OTTAWA   (Canada)

^c ST MICHAEL'S HOSPITAL   (Canada)

^d OTTAWA HOSPITAL RESEARCH INSTITUTE   (Canada)

^e Ottawa Hospital Research Institute ^*  (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

AZATHIOPRINE; MERCAPTOPURINE; THIOPURINE METHYLTRANSFERASE;

CHRONIC INFLAMMATION; COCHRANE LIBRARY; EMBASE; ENZYME ACTIVITY; ENZYME ANALYSIS; GENOTYPE; HEALTH HAZARD; HETEROZYGOTE; HOMOZYGOTE; HUMAN; INFLAMMATORY DISEASE; MEDLINE; PRIORITY JOURNAL; RANDOMIZED CONTROLLED TRIAL (TOPIC); REVIEW; RISK REDUCTION; SENSITIVITY AND SPECIFICITY; SYSTEMATIC REVIEW;

EID: 79959652551     PISSN: 00034819     EISSN: 15393704     Source Type: Journal    
DOI: 10.7326/0003-4819-154-12-201106210-00009     Document Type: Review

References (98)

1. Prefontaine E, Sutherland LR, Macdonald JK, Cepoiu M. Azathioprine or 6-mercaptopurine for maintenance of remission in Crohn's disease. Cochrane Database Syst Rev. 2009:CD000067. [PMID: 19160175]
2. Gisbert JP, Gomollón F. Thiopurine-induced myelotoxicity in patients with inflammatory bowel disease: a review. Am J Gastroenterol. 2008;103:1783-1800. [PMID: 18557712]
3. Meggitt SJ, Reynolds NJ. Azathioprine for atopic dermatitis. Clin Exp Der-matol. 2001;26:369-375. [PMID: 11488818]
4. Swann PF, Waters TR, Moulton DC, Xu YZ, Zheng Q, Edwards M, et al. Role of postreplicative DNA mismatch repair in the cytotoxic action of thiogua-nine. Science. 1996;273:1109-1111. [PMID: 8688098]
5. Collie-Duguid ES, Pritchard SC, Powrie RH, Sludden J, Collier DA, Li T, et al. The frequency and distribution of thiopurine methyltransferase alleles in Caucasian and Asian populations. Pharmacogenetics. 1999;9:37-42. [PMID: 10208641]
6. Engen RM, Marsh S, Van Booven DJ, McLeod HL. Ethnic differences in pharmacogenetically relevant genes. Curr Drug Targets. 2006;7:1641-1648. [PMID: 17168839]
7. Hon YY, Fessing MY, Pui CH, Relling MV, Krynetski EY, Evans WE. Polymorphism of the thiopurine S-methyltransferase gene in African-Americans. Hum Mol Genet. 1999;8:371-376. [PMID: 9931346]
8. Ameyaw MM, Collie-Duguid ES, Powrie RH, Ofori-Adjei D, McLeod HL. Thiopurine methyltransferase alleles in British and Ghanaian populations. Hum Mol Genet. 1999;8:367-370. [PMID: 9931345]
9. Efrati E, Adler L, Krivoy N, Sprecher E. Distribution of TPMT risk alleles for thiopurine [correction of thioupurine] toxicity in the Israeli population. Eur J Clin Pharmacol. 2009;65:257-262. [PMID: 19048244]
10. Weyer N, Kröplin T, Fricke L, Iven H. Human thiopurine S-methyltransferase activity in uremia and after renal transplantation. Eur J Clin Pharmacol. 2001;57:129-136. [PMID: 11417444]
11. Kurzawski M, Gawronska-Szklarz B, Drozdzik M. Frequency distribution of thiopurine S-methyltransferase alleles in a polish population. Ther Drug Monit. 2004;26:541-545. [PMID: 15385838]
12. McLeod HL, Pritchard SC, Githang'a J, Indalo A, Ameyaw MM, Powrie RH, et al. Ethnic differences in thiopurine methyltransferase pharmacogenetics: evidence for allele specificity in Caucasian and Kenyan individuals. Pharmacogenetics. 1999;9:773-776. [PMID: 10634140]
13. Colombel JF, Ferrari N, Debuysere H, Marteau P, Gendre JP, Bonaz B, et al. Genotypic analysis of thiopurine S-methyltransferase in patients with Crohn's disease and severe myelosuppression during azathioprine therapy. Gastroenterology. 2000;118:1025-1030. [PMID: 10833476]
14. Anstey AV, Wakelin S, Reynolds NJ.; British Association of Dermatologists Therapy, Guidelines and Audit Subcommittee. Guidelines for prescribing azathioprine in dermatology. Br J Dermatol. 2004;151:1123-1132. [PMID: 15606506]
15. Lichtenstein GR, Abreu MT, Cohen R, Tremaine W.; American Gastroenterological Association. American Gastroenterological Association Institute medical position statement on corticosteroids, immunomodulators, and infliximab in inflammatory bowel disease. Gastroenterology. 2006;130:935-939. [PMID: 16530531]
16. Center for Drug Evaluation and Research. Overview:Imuran. Silver Spring, MD: U.S. Food and Drug Administration. Accessed at www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm?fuseaction=Search.Overview&DrugName=IMURAN on 6 May 2011.
17. Payne K, Newman W, Fargher E, Tricker K, Bruce IN, Ollier WE. TPMT testing in rheumatology: any better than routine monitoring? [Editorial]. Rheumatology (Oxford). 2007;46:727-729. [PMID: 17255139]
18. Whiting P, Rutjes AW, Reitsma JB, Bossuyt PM, Kleijnen J. The development of QUADAS: a tool for the quality assessment of studies of diagnostic accuracy included in systematic reviews. BMC Med Res Methodol. 2003;3:25. [PMID: 14606960]
19. Owens DK, Lohr KN, Atkins D, Treadwell JR, Reston JT, Bass EB, et al. AHRQ series paper 5: grading the strength of a body of evidence when comparing medical interventions-agency for healthcare research and quality and the effective health-care program. J Clin Epidemiol. 2010;63:513-523. [PMID: 19595577]
20. Stuart A, Ord JK, Arnold SF, O'Hagan A, Forster J. Kendalls Advanced Theory of Statistics. 6th ed. New York: J Wiley; 1994.
21. Bradburn MJ, Deeks JJ, Berlin JA, Russell Localio A. Much ado about nothing: a comparison of the performance of meta-analytical methods with rare events. Stat Med. 2007;26:53-77. [PMID: 16596572]
22. Stassen PM, Derks RP, Kallenberg CG, Stegeman CA. Thiopurinemethyl-transferase (TPMT) genotype and TPMT activity in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis: relation to azathioprine maintenance treatment and adverse effects [Letter]. Ann Rheum Dis. 2009;68: 758-759. [PMID: 19366895]
23. Ansari A, Arenas M, Greenfield SM, Morris D, Lindsay J, Gilshenan K, et al. Prospective evaluation of the pharmacogenetics of azathioprine in the treatment of inflammatory bowel disease. Aliment Pharmacol Ther. 2008;28:973-983. [PMID: 18616518]
24. Shah JA, Edwards CM, Probert CS. Should azathioprine and 5-aminosalicylates be coprescribed in inflammatory bowel disease? An audit of adverse events and outcome. Eur J Gastroenterol Hepatol. 2008;20:169-173. [PMID: 18301295]
25. Bezier M, Reguiai Z, Vitry F, Broly F, Bernard P. Thiopurine S-methyltransferase genotypic analysis in autoimmune bullous diseases. Eur J Dermatol. 2008;18:512-517. [PMID: 18693152]
26. Firooz A, Ghandi N, Hallaji Z, Chams-Davatchi C, Valikhani M, Kar-bakhsh Davari M. Role of thiopurine methyltransferase activity in the safety and efficacy of azathioprine in the treatment of pemphigus vulgaris. Arch Dermatol. 2008;144:1143-1147. [PMID: 18794458]
27. Gardiner SJ, Gearry RB, Begg EJ, Zhang M, Barclay ML. Thiopurine dose in intermediate and normal metabolizers of thiopurine methyltransferase may differ three-fold. Clin Gastroenterol Hepatol. 2008;6:654-660. [PMID: 18467186]
28. Palmieri O, Latiano A, Bossa F, Vecchi M, D'Inca R, Guagnozzi D, et al. Sequential evaluation of thiopurine methyltransferase, inosine triphosphate pyrophosphatase, and HPRT1 genes polymorphisms to explain thiopurines' toxicity and efficacy. Aliment Pharmacol Ther. 2007;26:737-745. [PMID: 17697207]
29. Winter JW, Gaffney D, Shapiro D, Spooner RJ, Marinaki AM, Sanderson JD, et al. Assessment of thiopurine methyltransferase enzyme activity is superior to genotype in predicting myelosuppression following azathioprine therapy in patients with inflammatory bowel disease. Aliment Pharmacol Ther. 2007;25: 1069-1077. [PMID: 17439508]
30. Tamori A, Shinzaki M, Kosaka S, Hayashi T, Iwai S, Enomoto M, et al. Thiopurine S-methyltransferase gene polymorphism in Japanese patients with autoimmune liver diseases. Liver Int. 2007;27:95-100. [PMID: 17241387]
31. Stocco G, Martelossi S, Barabino A, Decorti G, Bartoli F, Montico M, et al. Glutathione-S-transferase genotypes and the adverse effects of azathioprine in young patients with inflammatory bowel disease. Inflamm Bowel Dis. 2007; 13:57-64. [PMID: 17206640]
32. Gisbert JP, Niño P, Rodrigo L, Cara C, Guijarro LG. Thiopurine methyltransferase (TPMT) activity and adverse effects of azathioprine in inflammatory bowel disease: long-term follow-up study of 394 patients. Am J Gastroenterol. 2006;101:2769-2776. [PMID: 17026564]
33. Lindqvist M, Hindorf U, Almer S, Soderkvist P, Strom M, Hjortswang H, et al. No induction of thiopurine methyltransferase during thiopurine treatment in inflammatory bowel disease. Nucleosides Nucleotides Nucleic Acids. 2006;25: 1033-1037. [PMID: 17065060]
34. Banerjee S, Bishop WP. Evolution of thiopurine use in pediatric inflammatory bowel disease in an academic center. J Pediatr Gastroenterol Nutr. 2006;43: 324-330. [PMID: 16954954]
35. Schedel J, Godde A, Schütz E, Bongartz TA, Lang B, Scholmerich J, et al. Impact of thiopurine methyltransferase activity and 6-thioguanine nucleotide concentrations in patients with chronic inflammatory diseases. Ann N Y Acad Sci. 2006;1069:477-491. [PMID: 16855176]
36. Hindorf U, Lindqvist M, Hildebrand H, Fagerberg U, Almer S. Adverse events leading to modification of therapy in a large cohort of patients with inflammatory bowel disease. Aliment Pharmacol Ther. 2006;24:331-342. [PMID: 16842460]
37. Czaja AJ, Carpenter HA. Thiopurine methyltransferase deficiency and azathioprine intolerance in autoimmune hepatitis. Dig Dis Sci. 2006;51:968-975. [PMID: 16773433]
38. De Ridder L, Van Dieren JM, Van Deventer HJ, Stokkers PC, Van der Woude JC, Van Vuuren AJ, et al. Pharmacogenetics of thiopurine therapy in paediatric IBD patients. Aliment Pharmacol Ther. 2006;23:1137-1141. [PMID: 16611274]
39. Zelinkova Z, Derijks LJ, Stokkers PC, Vogels EW, van Kampen AH, Curvers WL, et al. Inosine triphosphate pyrophosphatase and thiopurine s-methyltransferase genotypes relationship to azathioprine-induced myelosuppression. Clin Gastroenterol Hepatol. 2006;4:44-49. [PMID: 16431304]
40. Jun JB, Cho DY, Kang C, Bae SC. Thiopurine S-methyltransferase polymorphisms and the relationship between the mutant alleles and the adverse effects in systemic lupus erythematosus patients taking azathioprine. Clin Exp Rheumatol. 2005;23:873-876. [PMID: 16396707]
41. Stocco G, Martelossi S, Barabino A, Fontana M, Lionetti P, Decorti G, et al. TPMT genotype and the use of thiopurines in paediatric inflammatory bowel disease. Dig Liver Dis. 2005;37:940-945. [PMID: 16202677]
42. von Ahsen N, Armstrong VW, Behrens C, von Tirpitz C, Stallmach A, Herfarth H, et al. Association of inosine triphosphatase 94C>A and thiopurine S-methyltransferase deficiency with adverse events and study drop-outs under azathioprine therapy in a prospective Crohn disease study. Clin Chem. 2005;51: 2282-2288. [PMID: 16214825]
43. Okada Y, Nakamura K, Kodama T, Ueki K, Tsukada Y, Maezawa A, et al. Thiopurine methyltransferase genotype and phenotype status in Japanese patients with systemic lupus erythematosus. Biol Pharm Bull. 2005;28:2117-2119. [PMID: 16272700]
44. Gearry RB, Roberts RL, Barclay ML, Kennedy MA. Lack of association between the ITPA 94C>A polymorphism and adverse effects from azathioprine. Pharmacogenetics. 2004;14:779-781. [PMID: 15564886]
45. Hindorf U, Lyrenas E, Nilsson A, Schmiegelow K. Monitoring of long-term thiopurine therapy among adults with inflammatory bowel disease. Scand J Gastroenterol. 2004;39:1105-1112. [PMID: 15545169]
46. Derijks LJ, Gilissen LP, Engels LG, Bos LP, Bus PJ, Lohman JJ, et al. Pharmacokinetics of 6-mercaptopurine in patients with inflammatory bowel disease: implications for therapy. Ther Drug Monit. 2004;26:311-318. [PMID: 15167634]
47. Marinaki AM, Ansari A, Duley JA, Arenas M, Sumi S, Lewis CM, et al. Adverse drug reactions to azathioprine therapy are associated with polymorphism in the gene encoding inosine triphosphate pyrophosphatase (ITPase). Pharmaco-genetics. 2004;14:181-187. [PMID: 15167706]
48. Haglund S, Lindqvist M, Almer S, Peterson C, Taipalensuu J. Pyrosequenc-ing of TPMT alleles in a general Swedish population and in patients with inflammatory bowel disease. Clin Chem. 2004;50:288-295. [PMID: 14656901]
49. Reuther LO, Sonne J, Larsen NE, Larsen B, Christensen S, Rasmussen SN, et al. Pharmacological monitoring of azathioprine therapy. Scand J Gastroenterol. 2003;38:972-977. [PMID: 14531535]
50. Hibi T, Naganuma M, Kitahora T, Kinjyo F, Shimoyama T. Low-dose azathioprine is effective and safe for maintenance of remission in patients with ulcerative colitis. J Gastroenterol. 2003;38:740-746. [PMID: 14505127]
51. Marinaki AM, Arenas M, Khan ZH, Lewis CM, Shobowale-Bakreel M, Escuredo E, et al. Genetic determinants of the thiopurine methyltransferase intermediate activity phenotype in British Asians and Caucasians. Pharmacogenet-ics. 2003;13:97-105. [PMID: 12563179]
52. Corominas H, Domènech M, Laíz A, Gich I, Geli C, Díaz C, et al. Is thiopurine methyltransferase genetic polymorphism a major factor for withdrawal of azathioprine in rheumatoid arthritis patients? Rheumatology (Oxford). 2003; 42:40-45. [PMID: 12509611]
53. Ansari A, Hassan C, Duley J, Marinaki A, Shobowale-Bakre EM, Seed P, et al. Thiopurine methyltransferase activity and the use of azathioprine in inflammatory bowel disease. Aliment Pharmacol Ther. 2002;16:1743-1750. [PMID: 12269967]
54. Langley PG, Underhill J, Tredger JM, Norris S, McFarlane IG. Thiopurine methyltransferase phenotype and genotype in relation to azathioprine therapy in autoimmune hepatitis. J Hepatol. 2002;37:441-447. [PMID: 12217596]
55. Schwab M, Schäffeler E, Marx C, Fischer C, Lang T, Behrens C, et al. Azathioprine therapy and adverse drug reactions in patients with inflammatory bowel disease: impact of thiopurine S-methyltransferase polymorphism. Pharma-cogenetics. 2002;12:429-436. [PMID: 12172211]
56. Dubinsky MC, Yang H, Hassard PV, Seidman EG, Kam LY, Abreu MT, et al. 6-MP metabolite profiles provide a biochemical explanation for 6-MP resistance in patients with inflammatory bowel disease. Gastroenterology. 2002; 122:904-915. [PMID: 11910342]
57. Kader HA, Wenner WJ Jr, Telega GW, Maller ES, Baldassano RN. Normal thiopurine methyltransferase levels do not eliminate 6-mercaptopurine or azathioprine toxicity in children with inflammatory bowel disease. J Clin Gastro-enterol. 2000;30:409-413. [PMID: 10875470]
58. Dubinsky MC, Lamothe S, Yang HY, Targan SR, Sinnett D, Théorêt Y, et al. Pharmacogenomics and metabolite measurement for 6-mercaptopurine therapy in inflammatory bowel disease. Gastroenterology. 2000;118:705-713. [PMID: 10734022]
59. Ishioka S, Hiyama K, Sato H, Yamanishi Y, McLeod HL, Kumagai K, et al. Thiopurine methyltransferase genotype and the toxicity of azathioprine in Japanese. Intern Med. 1999;38:944-947. [PMID: 10628931]
60. Black AJ, McLeod HL, Capell HA, Powrie RH, Matowe LK, Pritchard SC, et al. Thiopurine methyltransferase genotype predicts therapy-limiting severe tox-icity from azathioprine. Ann Intern Med. 1998;129:716-718. [PMID: 9841604]
61. Stolk JN, Boerbooms AM, de Abreu RA, de Koning DG, van Beusekom HJ, Muller WH, et al. Reduced thiopurine methyltransferase activity and development of side effects of azathioprine treatment in patients with rheumatoid arthritis. Arthritis Rheum. 1998;41:1858-1866. [PMID: 9778228]
62. Snow JL, Gibson LE. The role of genetic variation in thiopurine methyl-transferase activity and the efficacy and/or side effects of azathioprine therapy in dermatologic patients. Arch Dermatol. 1995;131:193-197. [PMID: 7857117]
63. Lennard L, Van Loon JA, Weinshilboum RM. Pharmacogenetics of acute azathioprine toxicity: relationship to thiopurine methyltransferase genetic polymorphism. Clin Pharmacol Ther. 1989;46:149-154. [PMID: 2758725]
64. Stocco G, Martelossi S, Decorti G, Ventura A, Malusa N, Bartoli F, et al. Pharmacogenetics of thiopurines: can posology be guided by laboratory data? Radiol Oncol. 2004;38:101-109.
65. Jojic N, Urosevic J, Bojic B, Pavlovic S. Determination of thiopurine meth-yltransferase genotype in the patients with inflammatory bowel disease before and during azathioprine therapy. Arch Gastroenterohepatol. 2003;22:5-9.
66. Kim JH, Cheon JH, Hong SS, Eun CS, Byeon JS, Hong SY, et al. Can we predict highly frequent myelotoxicity during azathioprine/6-mercaptopurine treatment in Korean patients with inflammatory bowel disease by thiopurine methyltransferase genotyping and phenotyping or inosine triphosphate pyrophos-phatase geno journal>A multicenter study. Gastroenterology. 2008;134:A210.
67. Schmeling H, Abdelhaleem M, Benseler S, Tyrrell P, Silverman E. Role of TPMT genotyping and azathioprine metabolites in predicting toxicity of azathio-prine in PSLE patients. Arthritis Rheum. 2007;56:4265-4266.
68. Lopez AJ, Schwab M, Witt H, Ansari A, Dejaco C, Schaeffeler E, et al. The impact of genetic variants in TPMT, ITPA, MTHFR, SPINK1 and PRSS1 on azathioprine-induced pancreatitis. Gastroenterology. 2006;130(4 Suppl 2).
69. van Dieren J, van Vuuren H, Kuipers E, Kusters H, Nieuwenhuis E, van der Woude J. Heterozygous polymorphisms in the genes encoding ITPA and TPMT*3A are not predictive for the development of adverse effects of azathio-prine treatment in IBD patients. Gastroenterology. 2005;128(4 Suppl 2).
70. Seddik M, Texier F, Ferrari N, Cortot A, Libersa C, Broly F, et al. Thio-purine S-methyltransferase genotyping does not predict azathioprine-induced myelosuppression in Crohn's disease. AGA Abstract S1311. Digestive Disease Week, Orlando, Florida, 18-21 May 2003.
71. Tani C, Mosca M, Colucci R, Gori G, d'Ascanio A, Ghisu N, et al. Genetic polymorphisms of thiopurine S-methyltransferase in a cohort of patients with systemic autoimmune diseases. Clin Exp Rheumatol. 2009;27:321-324. [PMID: 19473575]
72. Hindorf U, Jahed K, Bergquist A, Verbaan H, Prytz H, Wallerstedt S, et al. Characterisation and utility of thiopurine methyltransferase and thiopurine metabolite measurements in autoimmune hepatitis. J Hepatol. 2010;52:106-111. [PMID: 19906459]
73. Vestergaard T, Bygum A. An audit of thiopurine methyltransferase genotyp-ing and phenotyping before intended azathioprine treatment for dermatological conditions. Clin Exp Dermatol. 2010;35:140-144. [PMID: 19663853]
74. Kolorz M, Bartosova L, Hosek J, Dvorackova D, Chylkova A, Zboril V, et al. Importance of thiopurine S-Methyltransferase gene polymorphisms for prediction of azathioprine toxicity. Neuro Endocrinol Lett. 2009;30 Suppl 1:137-142. [PMID: 20027160]
75. Newman W, Payne K, Tricker K, Roberts S, Fargher E, Pushpakom S, et al. A pragmatic randomised controlled trial of thiopurine methyltransferase genotyping prior to azathioprine treatment: the TARGET study. Pharmacog-enomics. 2011. [Forthcoming].
76. Kim JH, Cheon JH, Hong SS, Eun CS, Byeon JS, Hong SY, et al. Influences of thiopurine methyltransferase genotype and activity on thiopurine-induced leukopenia in Korean patients with inflammatory bowel disease: a retrospective cohort study. J Clin Gastroenterol. 2010;44:e242-e248. [PMID: 20308917]
77. Sahasranaman S, Howard D, Roy S. Clinical pharmacology and pharmaco-genetics of thiopurines. Eur J Clin Pharmacol. 2008;64:753-767. [PMID: 18506437]
78. Schaeffeler E, Fischer C, Brockmeier D, Wernet D, Moerike K, Eichel-baum M, et al. Comprehensive analysis of thiopurine S-methyltransferase phenotype-genotype correlation in a large population of German-Caucasians and identification of novel TPMT variants. Pharmacogenetics. 2004;14:407-417. [PMID: 15226673]
79. Higgs JE, Payne K, Roberts C, Newman WG. Are patients with intermediate TPMT activity at increased risk of myelosuppression when taking thiopurine medications? Pharmacogenomics. 2010;11:177-188. [PMID: 20136357]
80. Ford L, Kampanis P, Berg J. Thiopurine S-methyltransferase genotype-phenotype concordance: used as a quality assurance tool to help control the phenotype assay. Ann Clin Biochem. 2009;46:152-154. [PMID: 19164342]
81. Sanderson J, Ansari A, Marinaki T, Duley J. Thiopurine methyltransferase: should it be measured before commencing thiopurine drug therapy? Ann Clin Biochem. 2004;41:294-302. [PMID: 15298741]
82. Ford LT, Berg JD. Thiopurine S-methyltransferase (TPMT) assessment prior to starting thiopurine drug treatment; a pharmacogenomic test whose time has come. J Clin Pathol. 2010;63:288-295. [PMID: 20354201]
83. Payne K, Newman WG, Gurwitz D, Ibarreta D, Phillips KA. TPMT testing in azathioprine: A 'cost-effective use of healthcare resources'? Personaliz Med. 2009;6:103-113.
84. Chakravarty K, McDonald H, Pullar T, Taggart A, Chalmers R, Oliver S, et al; British Society for Rheumatology, British Health Professionals in Rheumatology Standards, Guidelines and Audit Working Group. BSR/BHPR guideline for disease-modifying anti-rheumatic drug (DMARD) therapy in consultation with the British Association of Dermatologists. Rheumatology (Oxford). 2008;47:924-925. [PMID: 16940305]
85. Carter MJ, Lobo AJ, Travis SP.; IBD Section, British Society of Gastroen-terology. Guidelines for the management of inflammatory bowel disease in adults. Gut. 2004;53 Suppl 5:V1-V16. [PMID: 15306569]
86. Wang L, Pelleymounter L, Weinshilboum R, Johnson JA, Hebert JM, Altman RB, et al. Very important pharmacogene summary: thiopurine S-methyltransferase. Pharmacogenet Genomics. 2010;20:401-405. [PMID: 20154640]
87. Arenas M, Duley J, Sumi S, Sanderson J, Marinaki A. The ITPA c.94C>A and g.IVS2 + 21A>C sequence variants contribute to missplicing of the ITPA gene. Biochim Biophys Acta. 2007;1772:96-102. [PMID: 17113761]
88. Salavaggione OE, Wang L, Wiepert M, Yee VC, Weinshilboum RM. Thiopurine S-methyltransferase pharmacogenetics: variant allele functional and comparative genomics. Pharmacogenet Genomics. 2005;15:801-815. [PMID: 16220112]
89. Ujiie S, Sasaki T, Mizugaki M, Ishikawa M, Hiratsuka M. Functional characterization of 23 allelic variants of thiopurine S-methyltransferase gene (TPMT*2-*24). Pharmacogenet Genomics. 2008;18:887-893. [PMID: 18708949]
90. Otterness D, Szumlanski C, Lennard L, Klemetsdal B, Aarbakke J, Park-Hah JO, et al. Human thiopurine methyltransferase pharmacogenetics: gene sequence polymorphisms. Clin Pharmacol Ther. 1997;62:60-73. [PMID: 9246020]
91. Hamdan-Khalil R, Allorge D, Lo-Guidice JM, Cauffiez C, Chevalier D, Spire C, et al. In vitro characterization of four novel non-functional variants of the thiopurine S-methyltransferase. Biochem Biophys Res Commun. 2003;309: 1005-1010. [PMID: 13679074]
92. Hamdan-Khalil R, Gala JL, Allorge D, Lo-Guidice JM, Horsmans Y, Hou-dret N, et al. Identification and functional analysis of two rare allelic variants of the thiopurine S-methyltransferase gene, TPMT*16 and TPMT*19. Biochem Pharmacol. 2005;69:525-529. [PMID: 15652243]
93. Schaeffeler E, Eichelbaum M, Reinisch W, Zanger UM, Schwab M. Three novel thiopurine S-methyltransferase allelic variants (TPMT*20, *21, *22)-association with decreased enzyme function. Hum Mutat. 2006;27:976. [PMID: 16917910]
94. Sasaki T, Goto E, Konno Y, Hiratsuka M, Mizugaki M. Three novel single nucleotide polymorphisms of the human thiopurine S-methyltransferase gene in Japanese individuals. Drug Metab Pharmacokinet. 2006;21:332-336. [PMID: 16946561]
95. Lindqvist M, Skoglund K, Karlgren A, Soderkvist P, Peterson C, Kidhall I, et al. Explaining TPMT genotype/phenotype discrepancy by haplotyping of TPMT*3A and identification of a novel sequence variant, TPMT*23. Pharmacogenet Genomics. 2007;17:891-895. [PMID: 17885628]
96. Garat A, Cauffiez C, Renault N, Lo-Guidice JM, Allorge D, Chevalier D, et al. Characterisation of novel defective thiopurine S-methyltransferase allelic variants. Biochem Pharmacol. 2008;76:404-415. [PMID: 18602085]
97. Kham SK, Soh CK, Aw DC, Yeoh AE. TPMT*26 (208F->L), a novel mutation detected in a Chinese. Br J Clin Pharmacol. 2009;68:120-123. [PMID: 19660010]
98. Feng Q, Vannaprasaht S, Peng Y, Angsuthum S, Avihingsanon Y, Yee VC, et al. Thiopurine S-methyltransferase pharmacogenetics: functional characterization of a novel rapidly degraded variant allozyme. Biochem Pharmacol. 2010;79: 1053-1061. [PMID: 19945438]