RESUMEN
BACKGROUND: First Nations in the Canadian province of Manitoba have disproportionately high rates of epidemic and endemic TB. Gene polymorphisms that modulate HLA Class I and II antigens are among the risk markers for TB, along with other biologic, and social determinants of health. HLA-A, B, DRB1, DQA1, DQB1 were typed in two Manitoba First Nation indigenous groups to identify and compare the frequency of gene polymorphisms that may influence susceptibility or resistance to TB. METHODS: Participants who self-identified as either Dene or Cree enrolled into the study from two First Nation communities in Manitoba, Canada. Genomic DNA was extracted from blood samples collected with informed consent from Dene (N=63) and Cree (N=42) First Nation study participants. Participants self-reported having treated active TB, treated latent TB or no TB. HLA Class I and II molecules were typed using sequence-specific oligonucleotide (SSO) probes from commercially available kits. RESULTS: The rates of treated active and latent TB were marginally higher among the Dene than the Cree participants (p=0.112). Class I and II HLA loci were in Hardy-Weinberg equilibrium in both the Dene and Cree groups. In this exploratory analysis of TB and HLA allele frequencies in Dene and Cree cohorts HLA-A*03 and HLA-DQB1*05:03 were significantly associated with TB. CONCLUSIONS: The high incidence of TB in both Dene and Cree populations in Canada requires both biomedical and socioeconomic prevention and control measures. Among the former, an understanding of HLA diversity among First Nations groups may aid the development of new effective vaccine and therapeutic modalities that depend on the interaction between small molecules and specific HLA epitopes.
Asunto(s)
Enfermedades Endémicas , Etnicidad , Antígeno HLA-A3/genética , Antígenos HLA-B/genética , Cadenas beta de HLA-DQ/genética , Tuberculosis Latente/epidemiología , Canadá , Estudios de Cohortes , Frecuencia de los Genes , Estudios de Asociación Genética , Cadenas alfa de HLA-DQ/genética , Cadenas HLA-DRB1/genética , Humanos , Polimorfismo Genético , PrevalenciaRESUMEN
The present study determined whether a pattern of functional single-nucleotide polymorphisms (SNPs) was present that could predispose a Dené cohort to a suboptimal response to Mycobacterium tuberculosis. Compared with a Caucasian cohort, the Dené and Cree were found to maintain a significantly higher frequency of SNPs associated with low expression of vitamin D receptor (VDR), interferon (IFN)-gamma (+874), and tumor necrosis factor-alpha (-308) and high production of monocyte chemoattractant protein (MCP)-1 (-2518) and interleukin (IL)-6 (-174). Given the roles played by IFN-gamma and VDR in facilitating macrophage containment of M. tuberculosis and the opposing role of MCP-1 and IL-6, the observed allelic variation by ethnicity may in part contribute to the high rates of tuberculosis among the Dené.
