IL4 and asthma: Our findings show that IL4-590*CT/TT genotypes associate to a 2.2-fold risk for asthma (2.4-fold for overall persistent asthma and 4-fold for moderate-severe persistent asthma) while IL4-590*T allele represents a 2-fold risk for asthma (2.2-fold for persistent asthma and 3.4-fold for moderate-severe asthma), compared to individuals harbouring other IL4-590 C/T genotypes or allele.