In a study of common variable immunodeficiency (23), high levels of IL-10 were recorded in serum of carriers of heterozygous genotypes C/T and C/A at loci -819 and -592, respectively, in comparison to patients homozygous to allele C. It is noteworthy to mention that these three IL-10 gene polymorphisms at loci -1082, -819 and -592 are probably in linkage disequilibrium with biologic significance (23). Here, IL10 is linked to immune system disorder.