Genetic analyses of thiopurine methyltransferase polymorphisms in Greenlandic and Danish populations

Aim : To determine the frequency of thiopurine methyltransferase (TPMT) low‐activity alleles in the Greenlandic and Danish populations. Methods : 142 Greenlandic individuals and 200 Danish blood donors were screened for the TPMT G460A and A719G low‐activity alleles. Results: Thiopurine methyltransferase low‐activity alleles were significantly higher in the Greenlandic compared to the Danish population, being 8.1% (95% CI 4.9–11.3) and 3.5% (95% CI 1.7–5.3) (p<0.01), respectively. Except for one Danish patient with an A719G allele (TPMT*3C), all the aberrant alleles were compound G460A and A719G alleles (TPMT*3A). Conclusion : In the Danish population, the incidence of thiopurine methyltransferase low‐activity alleles was found to be similar to other Caucasian populations previously described. In contrast, the Greenlandic population showed a significantly higher frequency of thiopurine methyltransferase low‐activity alleles.