min. The PCR products were separated by electrophoresis in a 2% agarose gel prepared with ethidium bromide. Three allele variants of the gene polymorphism were identified based on the PCR fragment sizes: short (S; 486bp, 14 repeats), long (L; 529bp, 16 repeats), or extra-long (XL; 612 or 654bp, 20 or 22 repeats). Subjects were classified into five genotypes: S/S, S/L, L/L, S/XL, and L/XL (no respondents were homozygous for the XL allele). The genotype frequencies are in Hardy-Weinberg equilibrium (χ2=2.59, df=3, p~0.46).
