Novel polymorphism in the 5'-untranslated region of the interleukin-4 gene.

We found a novel polymorphism C/T change at position -34 counting from the first ATG codon, of the interleukin-4 (IL-4) gene, located between the TATA box and the first ATG on exon 1. The allelic frequency of this C/T polymorphism in 64 independent Japanese samples was 0.37:0.63. In addition, PCR-restriction fragment length polymorphism analysis revealed that the -34T/T polymorphism was always associated with -590T/T, a known polymorphism that increases IL-4 transcriptional activity.