IL4 and childhood onset asthma: IL4 maps to a cytokine cluster on chromosome 5q31-q33.[43–45] It is a pro-inflammatory cytokine that is involved in a number of immunoregulatory pathways such as the induction of IgE synthesis by B-cells and differentiation of T-helper-type-2 lymphocytes.[43–46] IL4 has been linked to asthma phenotypes and atopy in several studies[43,44] including childhood populations.[45,47] In accordance with these findings, we found associations of two SNPs in IL4 with childhood asthma.