Fig. 1From: Thiopurine S-methyltransferase activity in Nigerians: phenotypes and activity reference valuesA frequency distribution histogram showing thiopurine S-methyltransferase activity, TPMT, activity values for 100 healthy, unrelated Nigerian subjects. U/g Hb: ‘unit per gram haemoglobin’ which is the amount of 6-methylmercaptopurine in ng/mL generated after a 1-h incubation at 37 °C per haemoglobin contentBack to article page