title: Interethnic difference in thiopurine methyltransferase activity.
abstract: A number of metabolic pathways are subject to both genetic polymorphism and interethnic differences. A catabolic pathway of 6-mercaptopurine, red blood cell (RBC) thiopurine methyltransferase (TPMT) activity showed genetic polymorphism in Caucasians, but variation according to ethnicity has not been studied. We investigated if red blood cell thiopurine methyltransferase was subject to interethnic variation in a Saami (Lappish; n = 36) and a Caucasian population (n = 50). The Saami population sample had 29% higher thiopurine methyltransferase activity, 17.0 +/- 3.3 U/ml red blood cell compared with the Caucasian population sample, 13.1 +/- 2.9 U/ml red blood cell (p much less than 0.001). Probit plots and frequency distribution histograms supported bimodality consistent with genetic polymorphism in both study populations. Differences in chronic diseases, drug consumption, age, or gender could not explain the interethnic difference in red blood cell thiopurine methyltransferase activity. The higher red blood cell thiopurine methyltransferase activity in the Saami population group indicates that these subjects may require higher dosages of thiopurine drugs than Caucasians.
authors.affiliation: Department of Pharmacology, University of Tromsø, Norway.
authors.forename: B
authors.initials: B
authors.lastname: Klemetsdal
authors.forename: E
authors.initials: E
authors.lastname: Tollefsen
authors.forename: T
authors.initials: T
authors.lastname: Loennechen
authors.forename: K
authors.initials: K
authors.lastname: Johnsen
authors.forename: E
authors.initials: E
authors.lastname: Utsi
authors.forename: K
authors.initials: K
authors.lastname: Gisholt
authors.forename: E
authors.initials: E
authors.lastname: Wist
authors.forename: J
authors.initials: J
authors.lastname: Aarbakke
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002415:Cats; D004912:Erythrocytes / Q000201:enzymology; D005006:Ethnicity / Q000235:genetics*; D005260:Female; D014644:Genetic Variation / Q000235:genetics*; D006801:Humans; D008297:Male; D008780:Methyltransferases / Q000097:blood / Q000235:genetics*; D008875:Middle Aged; D009664:Norway / Q000208:ethnology; D044465:White People / Q000235:genetics
chemical_list: D008780:Methyltransferases; C022745:thiopurine methyltransferase