Microheterogeneity and AMP-FLP analysis of the 3' flanking interleukin-6 VNTR polymorphism in central Spain

The 3' flanking region of the interleukin-6 gene is polymorphic due to the existence of a hyper-variable region consisting of a number of A + T rich variable repeated DNA sequences (VNTR). We used specific primers to amplify this particular VNTR system by PCR in 222 unrelated normal Spaniards from Madrid, Spain. A model of inheritance comprising of five different allele classes was proposed and frequencies evaluated as follows: B4, 0.635; B3.1, 0.029; B3, 0.270; B2, 0.038; B1, 0.027. Also, examples of inheritance of mendelian microheterogeneity are shown. Heterozigosity index was calculated (H = 0.5) and no departure from Hardy-Weinberg equilibrium was observed (chi 2 = 0.091, d. f. 1, p > 0.75).