Differences in IL33 and IL1RL1 frequencies were evaluated between patients with IgAV and healthy controls and between patients with IgAV stratified according to specific clinical characteristics of the disease (age at disease onset or presence/absence of GI or renal manifestations).
First, each IL33 and IL1RL1 polymorphism was analysed independently. Both genotype and allele frequencies were calculated and compared between the groups mentioned above by chi-square test. Strength of association was estimated using odds ratios (OR) and 95% confidence intervals (CI).
Then, allelic combinations (haplotypes) of both IL33 and IL1RL1 polymorphisms were carried out. Haplotype frequencies were calculated by the Haploview v4.2 software (
P-values were two-tailed and those lower than 0.05 were considered as statistically significant. All analyses were performed with the STATA statistical software 12/SE (Stata Corp., College Station, TX, USA).