['The single nucleotide polymorphism (SNP) at deoxyribonuclease I (DNase I) in exon 8 (A2317G: Gln222Arg) has been shown to be associated with several diseases.', 'The allele frequency of the DNASE1 polymorphism in Chinese (Shenyang and Guangzhou in China), Uygurs (Urumqi), Tamils (Sri Lanka), and Tibetans (Katmandu in Nepal) was investigated, and the results were compared with those of other studies.', 'This study revealed that DNASE1*1 is more common in Africans and DNASE1*2 is more common in Caucasians. Expression vectors of DNASE1*1 and DNASE1*2 were constructed and compared to the enzyme properties secreted into a medium from transfected COS-7 cells. The activity of the type-2 enzyme was significantly higher than that of the type-1 enzyme. In addition, the type-1 enzyme was heat-labile when compared to the type-2 enzyme. Moreover, the optimum pH of the DNase I type-2 enzyme was more acidic than that of DNase I type-1.'] Does gln222Arg ( A2317G ) polymorphism in the deoxyribonuclease I gene exhibit ethnic and functional differences?