HLA and MICA genes in patients with tuberculosis in Brazil

Positive association between MIC gene polymorphism and tuberculosis in Chinese population

The disease progression and morbidity of tuberculosis (TB) infections are determined by virulence of the micro-organism, host genetic factors and environmental factors. The highly polymorphic MHC class I chain-related gene (MIC) could serve as a potential host genetic candidate. To investigate the association of MIC polymorphism with TB infection, 124 patients and 191 ethnically matched controls from Hunan province, Southern China, were genotyped for the MIC polymorphism using polymerase chain reaction-sequence specific priming and sequencing-based typing. The results showed that allele frequencies of MIC-sequence and MICA-STR were different in TB patients in comparison to normal controls (both P < 0.05). MICA-A4 and MICA*012:01 alleles were positive associated (OR = 2.42, 95% CI: 1.69-3.87; OR = 3.41, 95% CI: 2.19-5.33, respectively, both P_c < 0.05) while MICA -A5 were inversely associated (OR = 0.59, 95%CI: 0.41-0.94, P_c < 0.05) with TB. Homozygote MICA*012:01/012:01 was observed to have significant risk effects on TB (OR = 4.76, 95% CI: 1.94-11.69, P_c0000-0001-5151-1853 < 0.05). Additionally, MICB*008 allele conduct a significant risk effect for TB (OR = 3.17, 95%CI: 1.80-5.61, P_c < 0.05). All the data showed that MIC polymorphism was associated with the variable susceptibility to TB in Chinese population.

Influence of Genetic Polymorphism Towards Pulmonary Tuberculosis Susceptibility

Tuberculosis (TB) is still remains the major threat for human health worldwide. Several case-control, candidate-gene, family studies and genome-wide association studies (GWAS) suggested the association of host genetic factors to TB susceptibility or resistance in various ethnic populations. Moreover, these factors modulate the host immune responses to tuberculosis. Studies have reported genetic markers to predict TB development in human leukocyte antigen (HLA) and non-HLA genes like killer immunoglobulin-like receptor (KIR), toll-like receptors (TLRs), cytokine/chemokines and their receptors, vitamin D receptor (VDR) and SLC11A1 etc. Highly polymorphic HLA loci may influence antigen presentation specificities by modifying peptide binding motifs. The recent meta-analysis studies revealed the association of several HLA alleles in particular class II HLA-DRB1 with TB susceptibility and valuable marker for disease development especially in Asian populations. Case-control studies have found the association of HLA-DR2 in some populations, but not in other populations, this could be due to an ethnic specific association of gene variants. Recently, GWAS conducted in case-control and family based studies in Russia, Chinese Han, Morocco, Uganda and Tanzania revealed the association of genes such as ASAP1, Alkylglycerol monooxygenase (AGMO), Forkhead BoxP1 (FOXP1), C-terminal domain phosphatase 1 (UBLCP1) and intergenic SNP rs932347C/T with TB. Whereas, SNP rs10956514A/G were not associated with TB in western Chinese Han and Tibetan population. In this review, we summarize the recent findings of genetic variants with susceptibility/resistance to TB.

[Association between HLA-A and HLA-DRB1 allele polymorphisms and susceptibility to tuberculosis in southern Chinese population]

OBJECTIVE

To study the relationship between HLA allele frequencies in peripheral blood mononuclear cells (PBMCs) and the susceptibility to tuberculosis in southern Chinese population.

METHODS

The polymorphisms of HLA-A and HLA-DRB1 loci in the PBMCs were analyzed in 294 patients with active tuberculosis using polymerase chain reaction-sequence based typing (PCT-SBT). The allele frequencies in the patients were compared with the data from 644 control southern Chinese subjects obtained from the online database Allele Frequencies in Worldwide Population.

RESULTS

The frequencies of HLA-A^* 0101 and HLA-DRB1^*1454 alleles in the patient cohort with pulmonary tuberculosis were significantly higher than those in the control group (2.4% vs 0.6%, χ²=10.788, P=0.001, P_c=0.016; 7.5% vs 0%, χ²=69.850, P < 0.0001); the frequencies of HLA-DRB1^*1202 and HLA-DRB1^*1401 alleles were significantly lower in this patient cohort than in the control group (10.4% vs 16.1%, χ²=9.845, P=0.002, P_c=0.044; 0% vs 3.1%, χ²=18.520, P < 0.001).

CONCLUSIONS

The frequencies of HLA-A and HLA-DRB1 alleles are correlated with the susceptibility to active tuberculosis in this southern Chinese population. HLA-A^*0101, HLA-DRB1^*1454 and the other 3 alleles are likely susceptible genes to tuberculosis, while HLA-DRB1^*1202, HLA-DRB1^*1401 and the other 4 alleles can be protective genes in this population.

The Role of Host Genetics (and Genomics) in Tuberculosis

Familial risk of tuberculosis (TB) has been recognized for centuries. Largely through studies of mono- and dizygotic twin concordance rates, studies of families with Mendelian susceptibility to mycobacterial disease, and candidate gene studies performed in the 20th century, it was recognized that susceptibility to TB disease has a substantial host genetic component. Limitations in candidate gene studies and early linkage studies made the robust identification of specific loci associated with disease challenging, and few loci have been convincingly associated across multiple populations. Genome-wide and transcriptome-wide association studies, based on microarray (commonly known as genechip) technologies, conducted in the past decade have helped shed some light on pathogenesis but only a handful of new pathways have been identified. This apparent paradox, of high heritability but few replicable associations, has spurred a new wave of collaborative global studies. This review aims to comprehensively review the heritability of TB, critically review the host genetic and transcriptomic correlates of disease, and highlight current studies and future prospects in the study of host genomics in TB. An implicit goal of elucidating host genetic correlates of susceptibility to Mycobacterium tuberculosis infection or TB disease is to identify pathophysiological features amenable to translation to new preventive, diagnostic, or therapeutic interventions. The translation of genomic insights into new clinical tools is therefore also discussed.

MHC Class I Chain-Related Gene A Polymorphisms and Linkage Disequilibrium with HLA-B and HLA-C Alleles in Ocular Toxoplasmosis

This study investigated whether polymorphisms of the MICA (major histocompatibility complex class I chain-related gene A) gene are associated with eye lesions due to Toxoplasma gondii infection in a group of immunocompetent patients from southeastern Brazil. The study enrolled 297 patients with serological diagnosis of toxoplasmosis. Participants were classified into two distinct groups after conducting fundoscopic exams according to the presence (n = 148) or absence (n = 149) of ocular scars/lesions due to toxoplasmosis. The group of patients with scars/lesions was further subdivided into two groups according to the type of the ocular manifestation observed: primary (n = 120) or recurrent (n = 28). Genotyping of the MICA and HLA alleles was performed by the polymerase chain reaction-sequence specific oligonucleotide technique (PCR-SSO; One Lambda®) and the MICA-129 polymorphism (rs1051792) was identified by nested polymerase chain reaction (PCR-RFLP). Significant associations involving MICA polymorphisms were not found. Although the MICA*002~HLA-B*35 haplotype was associated with increased risk of developing ocular toxoplasmosis (P-value = 0.04; OR = 2.20; 95% CI = 1.05–4.60), and the MICA*008~HLA-C*07 haplotype was associated with protection against the development of manifestations of ocular toxoplasmosis (P-value = 0.009; OR: 0.44; 95% CI: 0.22–0.76), these associations were not statistically significant after adjusting for multiple comparisons. MICA polymorphisms do not appear to influence the development of ocular lesions in patients diagnosed with toxoplasmosis in this study population.

Polymorphisms in HLA-DRB1 gene and the risk of tuberculosis: a meta-analysis of 31 studies

PURPOSE

The HLA-DRB1 gene polymorphisms have been implicated in susceptibility to tuberculosis (TB). However, a large number of studies have reported inconclusive results. This study was conducted to investigate the relationship of HLA-DRB1 gene polymorphisms and TB risk by a meta-analysis.

METHODS

A search was performed in Embase, PubMed, Wanfang Database, and China National Knowledge Internet (CNKI) up to Jul 30, 2014. Odds ratio (OR) and 95% confidence interval (95% CI) were used to assess the association. Statistical analyses were calculated by STATA 11.0 software.

RESULTS

All 31 articles involving 3,416 cases and 4,515 controls were identified. The pooled results indicated a significant association between HLA-DRB1*04 (OR 1.22, 95% CI 1.00-1.48, P = 0.048), *09 (OR 1.50, 95% CI 1.08-2.08, P = 0.016), *10 (OR 1.23, 95% CI 1.01-1.49, P = 0.035), *11 (OR 0.72, 95% CI 0.53-0.99, P = 0.044), *15 (OR 1.40, 95% CI 1.14-1.73, P = 0.001), and *16 (OR 1.33, 95% CI 1.08-1.63, P = 0.007) gene polymorphisms and TB risk. In addition, the results also show no significant association between HLA-DRB1*01 (P = 0.748), *03 (P = 0.947), *07 (P = 0.966), *08 (P = 0.440), *12 (P = 0.288), *13 (P = 0.241), and *14 (P = 0.551) gene polymorphisms and TB risk.

CONCLUSIONS

This study suggested that the HLA-DRB1*04, *09, *10, *15, and *16 gene polymorphisms may contribute to the risk of TB, especially in the East Asian. But the HLA-DRB1*11 gene polymorphism may be a protective factor for TB risk. Unfortunately, there is no significant association between the HLA-DRB1*01, *03, *07, *08, *12, *13, and *14 gene polymorphisms and TB risk.

Inherited susceptibility to CLL

Chronic lymphocytic leukaemia (CLL) is the most common lymphoid malignancy in Western countries, accounting for around a quarter of all leukaemias. Despite a strong familial basis to CLL, with risks in first-degree relatives of CLL cases being increased around sevenfold, the inherited genetic basis of CLL is currently largely unknown. The failure of genetic studies of CLL families to provide support for a major disease-causing locus has suggested a model of susceptibility based on the co-inheritance of multiple low-risk variants, some of which will be common. Recent genome-wide association studies of CLL have vindicated this model of inherited susceptibility to CLL, identifying common variants at multiple independent loci influencing risk. Here we review the evidence for inherited genetic predisposition to CLL and what the currently identified risk loci are telling us about the biology of CLL development.