RESUMO
Leprosy is a prevalent disease in Brazil, which ranks as the country with the second highest number of cases in the world. The disease manifests in a spectrum of forms, and genetic differences in the host can help to elucidate the immunopathogenesis. For a better understanding of MICA association with leprosy, we performed a casecontrol and a familybased study in two endemic populations in Brazil. MICA and HLAB alleles were evaluated in 409 leprosy patients and in 419 healthy contacts by PCRSSOPLuminexbased technology. In the familial study, analysis of 46 families was completed by direct sequencing of all exons and 3'/5'untranslated regions, using the Ilumina MiSeq platform. All data were collected between 2006 and 2009. Statistical analysis was performed using the Chisquare or Fisher's exact test together with a multivariate analysis. Familybased association was assessed by transmission disequilibrium test (TDT) software FBAT 2.0.4. We found associations between the haplotype MICA*002HLAB*35 with leprosy in both the per se and the multibacillary (MB) forms when compared to healthy contacts. The MICA allele *008 was associated with the clinical forms of paucibacillary (PB). Additionally, MICA*029 was associated with the clinical forms of MB. The association of MICA*029 allele (MICAA4 variant) with the susceptibility to the MB form suggests this variant for the transmembrane domain of the MICA molecule may be a risk factor for leprosy. Two MICA and nine HLAB variants were found associated with leprosy per se in the Colônia do Prata population. Linkage disequilibrium analysis revealed perfect linkage disequilibrium (LD) between HLAB markers rs2596498 and rs2507992, and high LD (R2 = .92) between these and the marker rs2442718. This familial study demonstrates that MICA association signals are not independent from those observed for HLAB. Our findings contribute the knowledge pool of the immunogenetics of Hansen's disease and reveals a new association of the MICA*029 allele(AU).