Polymorphisms in the TGFB1 and IL2RA genes are associated with clinical forms of leprosy in Brazilian population

BACKGROUND Leprosy is a chronic infectious disease caused by Mycobacterium leprae, and compromises the skin and peripheral nerves. This disease has been classified as multibacillary (MB) or paucibacillary (PB) depending on the host immune response. Genetic epidemiology studies in leprosy have shown the influence of human genetic components on the disease outcomes. OBJECTIVES We conducted an association study for IL2RA and TGFB1 genes with clinical forms of leprosy based on two case-control samples. These genes encode important molecules for the immunosuppressive activity of Treg cells and present differential expressions according to the clinical forms of leprosy. Furthermore, IL2RA is a positional candidate gene because it is located near the 10p13 chromosome region, presenting a linkage peak for PB leprosy. METHODS A total of 885 leprosy cases were included in the study; 406 cases from Rondonópolis County (start population), a hyperendemic region for leprosy in Brazil, and 479 cases from São Paulo state (replication population), which has lower epidemiological indexes for the disease. We tested 11 polymorphisms in the IL2RA gene and the missense variant rs1800470 in the TGFB1 gene. FINDINGS The AA genotype of rs2386841 in IL2RA was associated with the PB form in the start population. The AA genotype of rs1800470 in TGFB1 was associated with the MB form in the start population, and this association was confirmed for the replication population. MAIN CONCLUSIONS We demonstrated, for the first time, an association data with the PB form for a gene located on chromosome 10. In addition, we reported the association of TGFB1 gene with the MB form. Our results place these genes as candidates for validation and replication studies in leprosy polarisation.

Epidemiologia genética em hanseníase: estudo de associação da região genômica candidata 6p21 e do gene TLR1 / Genetic epidemiology of leprosy: association study of the genomic region 6p21 canditate and TLR1 gene

A hanseníase é uma doença infecciosa crônica, que acomete pele e sistema nervoso periférico e tem como agente etiológico o Mycobacterium leprae, um patógeno exclusivamente intracelular, que tem predileção por macrófagos e pelas células de Schwann. É um traço complexo e fatores genéticos do hospedeiro têm sido repetidamente implicados com o risco para a doença. A região cromossômica 6p21 vem sendo sistematicamente envolvida com a hanseníase, não só pelos genes do HLA de classe II, como também pelos estudos envolvendo marcadores em genes como o TNF e a LTA. O gene TLR1 também é um importante candidato e polimorfismos deste já têm sido associados com hanseníase per se e com reação hansênica. O objetivo desta pesquisa foi conduzir estudo de associação de base populacional do tipo caso-controle em hanseníase testando marcadores do tipo tag SNPs em genes candidatos da região cromossômica candidata 6p21 e do gene TLR1. Oitenta e nove marcadores do tipo tag SNPs, localizados em trinta e seis genes foram genotipados. O presente trabalho envolveu 1718 indivíduos, 981 casos e 737 controles, provenientes de dois estados brasileiros: Mato Grosso e São Paulo. As genotipagens da população de Rondonópolis, MT foram realizadas em plataforma de médio rendimento (VeraCode GoldenGate Genotyping Assay – Illumina) e as genotipagens da população de São Paulo foram feitas usando discriminação alélica baseada na tecnologia TaqMan (Applied Biosystems). Para as análises estatísticas foi empregado modelo de regressão logística, com correção para as co-variáveis etnia e sexo, usando o software R, para Windows. Treze genes localizados na região 6p21 tiveram marcadores associados com hanseníase per se. O alelo S do polimorfismo N248S do gene TLR1 também foi associado com susceptibilidade para hanseníase per se...

Leprosy is an chronic infectious disease that attacks skin and peripheral nervous system. The causative agent is Mycobacterium leprae, an obligate intracellular pathogen that infects macrophage and Schwann cells. It is a complex trait and host genetic factors have been extensively implicated in leprosy susceptibility. The chromosomal region 6p21 has been involved with leprosy susceptibility due to HLA class II, and TNF and LTA genes, as well. The TLR1 gene is also an important candidate gene and polymorphisms at this locus have been associated to leprosy per se and leprosy reactions. This research is a population-based association study in leprosy which tested tag SNPs located at candidate genes in chromosomal region 6p21 and in TLR1 gene. Eighty-nine markers distributed in thirty-six genes were genotyped. The present work enrolled 1,718 individuals, 981 cases and 737 controls from Mato Grosso and São Paulo States, Brazil. The genotypes for Rondonópolis population were obtained using by medium-scale genotyping platform (VeraCode GoldenGate Genotyping Assay – Illumina), while to São Paulo samples the genotyping were done by allelic discrimination based on TaqMan technology (Applied Biosystems). Statistical analysis were performed by logistic regression models adjusted for the covariates sex and ethnicity, using R software. Thirteen genes located at 6p21 region presented markers associated to leprosy per se. The S allele for N248S polymorphism at TLR1gene was also associated to leprosy susceptibility...