Frequency of a single nucleotide (A2317G) and 56-bp variable number of tandem repeat polymorphisms within the deoxyribonuclease I gene in five ethnic populations.

BACKGROUND

The single nucleotide polymorphism (SNP) at deoxyribonuclease I (DNase I), designated as DNASE1 (NCBI SNP number; 1053874), in exon 8 (A2317G) is considered to be one of the susceptibility genes for gastric and colorectal carcinoma and myocardial infarction. Recently, the presence of a variable number of tandem repeat (VNTR) polymorphisms, designated as HumDN1, in intron 4 was found.

METHODS

Simultaneous genotyping of the DNASE1 and HumDN1 polymorphisms within the DNase I gene was performed in Ovambo, Turkish, Mongolian, Korean, and Japanese populations.

RESULTS

The allele frequencies of the DNASE1 and HumDN1 loci differed among five populations. There was general uniformity for the two polymorphisms in the three Asian populations, but significant differences in genotype distribution between the Ovambo and Turkish populations. The DNASE1 *1 and HumDN1 *3 alleles were found to be the most predominant among the Ovambos. Turks had the highest allele frequency for DNASE1 *2, HumDN1 *4, and HumDN1 *5. A linkage disequilibrium between the single-nucleotide (A2317G) and 56-bp VNTR polymorphisms was revealed in all populations except the Ovambos.

CONCLUSIONS

This study is the first to demonstrate the simultaneous genotyping of DNASE1 and HumDN1 polymorphisms and reveal the existence of a certain genetic heterogeneity in the worldwide distribution of these two polymorphisms. The combination of the two polymorphisms within a DNase I gene may be potentially useful for clinical purposes and in population genetic studies.