Nucleotide tandem repeat alleles

Ethnic variation in allele frequencies can lead to important differences in disease susceptibility, outcome and drug metabolism [68, 69]. In addition to single nucleotide polymorphisms, variable number of tandem repeat (VNTR) regions have been shown to have functional significance. 

In a recent study, Mandola et al. showed that the 28 bp TSER tandem repeats contain elements that bind upstream stimulating factor (USF), and also that ligand binding by USF-1 and USF-2 enhances the transcriptional activity of the TS gene (Fig. 2) (42). Electrophoretic mobility shift analysis has shown that the presence of a G-to-C single nucleotide polymorphism (SNP) within the second repeat of the 3R allele leads to decreased ability of upstream stimulatory factor (USF) to bind within the repeat and therefore sequentially result in decreased transcriptional activity of the 3R TS gene variant (42). 

---