Structure of the human and murine IL-7 genes.

Human IL-7 locus consists of 6 exons and 9 introns with extensive 3′ and 5′ untranslated regions. The gene is located on chromosome 8q12-13. IL-7δ4 variant, which lacks exon 4, has been found in multiple tissues and lacks biologic activity. Whether this variant has any biologic significance is unknown. The murine IL-7 gene has approximately 80% homology to the human gene in the coding regions but lacks the 54–base pair (bp) exon 5.