Allele polymorphism and haplotype diversity of MICA/B in Tujia nationality of Zhangjiajie, Hunan Province, China

MICA and MICB allele assortment in Finland

Genetic variation in the MICA and MICB genes located within the major histocompatibility complex region has been reported to be associated with transplantation outcome and susceptibility to autoimmune diseases and infections. Only limited data of polymorphism in these genes in different populations are available. We here report allelic variation at 2-field resolution and the haplotypes of the MICA and MICB genes in Finland (n = 1032 individuals), a north European population with historical bottleneck and founder effects. Altogether 24 MICA and 18 MICB alleles were found, forming 70 estimated MICA-MICB haplotypes. As compared to other populations frequency differences were found, for example, MICA*010:01 was found to be at an allele frequency of 0.133 in Finland which is higher than in other European populations (0.021-0.077), but close to Asian populations (0.151-0.220). Three novel alleles with amino acid change are described. The results demonstrate a relatively high level of polymorphism and population differences in MICA and MICB allele distribution.

Association of MICA and HLA-B alleles with leprosy in two endemic populations in Brazil

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 case-control and a family-based study in two endemic populations in Brazil. MICA and HLA-B alleles were evaluated in 409 leprosy patients and in 419 healthy contacts by PCR-SSOP-Luminex-based 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 Chi-square or Fisher's exact test together with a multivariate analysis. Family-based association was assessed by transmission disequilibrium test (TDT) software FBAT 2.0.4. We found associations between the haplotype MICA*002-HLA-B*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 (MICA-A4 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 HLA-B variants were found associated with leprosy per se in the Colônia do Prata population. Linkage disequilibrium analysis revealed perfect linkage disequilibrium (LD) between HLA-B 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 HLA-B. Our findings contribute the knowledge pool of the immunogenetics of Hansen's disease and reveals a new association of the MICA*029 allele.

Relationship between the rs2596542 polymorphism in the MICA gene promoter and HBV/HCV infection-induced hepatocellular carcinoma: a meta-analysis

Background & aims

Various studies have investigated the relationship between the polymorphism, rs2596542, in the promoter of the major histocompatibility complex class I-related gene A (MICA) gene with susceptibility to hepatitis B virus (HBV)/ hepatitis C virus (HCV)-induced hepatocellular carcinoma (HCC); however, the results are inconclusive. This meta-analysis was conducted to investigate the relationship between rs2596542 and HCV/HBV-induced HCC.

Methods

Three electronic scientific publication databases (MEDLINE, Web of Science, and Embase) were screened using specific search terms and relevant literature identified using literature traceability methods. Selected publications were evaluated according to the inclusion and exclusion criteria, and 11 articles were included in the study. Effect size information (odds ratio [OR] and corresponding 95% confidence interval [CI]) were obtained following quality assessment and data extraction from the included publications, and a meta-analysis conducted.

Results

A total of 11 publications were included in the study, including 4582 patients with HCC and 21,095 non-HCC patients. TT genotype at rs2596542 was a risk factor for the development of HCC in patients with HCV/HBV infection (OR = 1.248, 95% CI: 1.040–1.499, P = 0.017), particularly those with HCV infection (OR = 1.326, 95% CI: 1.101–1.599, P = 0.003) and Asians (OR = 1.273, 95% CI: 1.002–1.618, P = 0.048), or when the control group was patients with chronic hepatitis C (CHC) (OR = 1.506, 95% CI: 1.172–1.936, P = 0.001).

Conclusion

The findings of this meta-analysis suggest that the rs2596542 variant in the MICA promoter region may affect MICA and soluble MICA (sMICA) protein expression, thereby influencing physiological vulnerability to HCC cells and the development of HCC. These data provide a theoretical basis for the diagnosis and treatment of patients with HCC and viral hepatitis infection.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0871-2) contains supplementary material, which is available to authorized users.

MICA and NKG2D: Is There an Impact on Kidney Transplant Outcome?

This paper aims to present an overview of MICA and natural killer group 2 member D (NKG2D) genetic and functional interactions and their impact on kidney transplant outcome. Organ transplantation has gone from what can accurately be called a “clinical experiment” to a routine and reliable practice, which has proven to be clinically relevant, life-saving and cost-effective when compared with non-transplantation management strategies of both chronic and acute end-stage organ failures. The kidney is the most frequently transplanted organ in the world (transplant-observatory¹). The two treatment options for end-stage renal disease (ESRD) are dialysis and/or transplantation. Compared with dialysis, transplantation is associated with significant improvements in quality of life and overall longevity. A strong relationship exists between allograft loss and human leukocyte antigens (HLA) antibodies (Abs). HLA Abs are not the only factor involved in graft loss, as multiple studies have shown that non-HLA antigens are also involved, even when a patient has a good HLA matche and receives standard immunosuppressive therapy. A deeper understanding of other biomarkers is therefore important, as it is likely to lead to better monitoring (and consequent success) of organ transplants. The objective is to fill the void left by extensive reviews that do not often dive this deep into the importance of MICA and NKG2D in allograft acceptance and their partnership in the immune response. There are few papers that explore the relationship between these two protagonists when it comes to kidney transplantation. This is especially true for the role of NKG2D in kidney transplantation. These reasons give a special importance to this review, which aims to be a helpful tool in the hands of researchers in this field.