Title Associations between IL12B polymorphisms and tuberculosis inthe Hong Kong Chinese population

Background. Interleukin (IL)–12 plays a vital role in regulating cell-mediated immunity against tuberculosis (TB). Methods. To test whether IL12B genetic polymorphisms might contribute to human TB susceptibility, we examined the genotype frequencies of 5 IL12B polymorphisms (at promoter, intron 2, intron 4, exon 5, and 3′ untranslated region [UTR]) in 516 patients with TB and 514 healthy control subjects from the Hong Kong Chinese population. Results. Individuals homozygous for the IL12B intron 2–repeat marker (ATT)8 had a 2.1-fold increased risk of developing TB ( ) (odds ratio, 2.14 [95 % confidence interval, 1.45–3.19]). Estimation of the frequenciesP!.001 of multiple-locus haplotypes composed of IL12B promoter, intron 2, intron 4, and 3 ′ UTR alleles revealed potential risk haplotypes (designated “A ” and “K”) and protective haplotypes (designated “B”) for TB. Furthermore, com-bining the genotype data of the 4 informative IL12B loci revealed a strong association between a specific genotype pattern, termed “diplotype I ” (heterozygous A and K haplotypes), and TB. In contrast, diplotype II (homozygous BB haplotypes) appeared protective against TB. Conclusions. These findings support the association between IL12B intron 2 polymorphism and TB and between specific IL12B haplotypes and TB