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Highlights • MICA-129 val/val genotype may influence sMICA expression. • The deficiency in heterozygotes found may be due LD of MICA and HLA alleles. • There was no difference between MICA- 129 Met/Val genotypes between samples. Abstract The aim of this case- control study was to investigate the association between preterm birth (PTB), MICA- 129 A/G dimorphism and sMICA levels. Fifty pregnant women with singleton pregnancy and previous PTB, or clinic diagnostic of threatened preterm labor in the actual pregnancy, or cervical length less than 25 mm and 50 healthy pregnant women were enrolled. DNA was extracted for genotyping for MICA -129 A/G by real-time PCR and sMICA plasma level was quantified by sandwich ELISA assay. Clinical and socioeconomic characteristics, results of TaqMan® genotyping and ELISA quantification were compared between the groups using qui-square, Fisher´s exact or Mann-Whitney test. A binary logistic regression model was used to predict PTB. The correlation between MICA -129 A/G genotypes and sMICA levels was investigated. There were not statistically significant differences between MICA -129 A/G polymorphism and sMICA plasma level.There was found a correlation between MICA -129 val/val genotype and higher levels of sMICA (ρ: -0.342; p:0.001). The presence of MICA -129 val/val genotype may be influencing sMICA expression. [ABSTRACT FROM AUTHOR]

The major histocompatibility complex (MHC) class I chain-related gene A (MICA) is located centromerically to the human leukocyte antigen (HLA)-B. The short distance between these loci in the MHC indicates the presence of linkage disequilibrium (LD). Similarly to the HLA, the MICA is highly polymorphic, and this polymorphism has not been well documented in different populations. In this study, we estimated the allelic frequencies of MICA and the linkage disequilibrium with HLA-B alleles in 346 renal-transplant candidates in southern Brazil. MICA and HLA were typed using the polymerase chain reaction-sequence-specific primer method (PCR-SSO), combined with the Luminex technology. A total of 19 MICA allele groups were identified. The most frequent allele groups were MICA*008 (21.6%), MICA*002 (17.0%) and MICA*004 (14.8%). The most common haplotypes were MICA*009-B*51 (7.8%), MICA*004-B*44 (6.06%) and MICA*002-B*35 (5.63%). As expected from the proximity of the MICA and HLA-B loci, most haplotypes showed strong LD. Renal patients and healthy subjects in the same region of Brazil showed statistically significant differences in their MICA polymorphisms. The MICA*027 allele group was more frequent in renal patients (Pc = 0.018, OR: 3.421, 95% CI: 1.516–7.722), while the MICA*019 allele group was more frequent in healthy subjects (Pc = 0.001, OR: 0.027, 95% CI: 0.002–0.469). This study provided information on the distribution of MICA polymorphisms and linkage disequilibrium with HLA-B alleles in Brazilian renal-transplant candidates. This information should help to determine the mechanisms of susceptibility to different diseases in patients with chronic kidney disease, and to elucidate the mechanisms involved in allograft rejection associated with MICA polymorphisms in a Brazilian population. [ABSTRACT FROM AUTHOR]

Problem HLA- G expression is related as an immune modulator of fetal-maternal tolerance, and its levels was correlated with pregnancy outcome. In a case-control study, we investigate the association between the genetic variability of the HLA-G gene and serum levels of soluble HLA-G in cases of embryo implantation failure. Method of Study Forty couples with at least two unsuccessful fresh embryo transfers (implantation failure; IF) and 83 fertile couples with at least two successful pregnancies was genotyped by sequencing-based typing. HLA- G alleles were defined by nucleotide sequence variations at exon 2, 3, and 4, and the quantification of soluble HLA- G (s HLA- G) was performed by ELISA. Results There was a significant difference between the HLA- G allelic distributions between IF couples and the control couples. The HLA-G*01:03:01 allele was increased in the IF couples. There were no significant differences in the serum levels of s HLA- G in the IF and control groups. Conclusion The results suggest that the distribution of HLA- G products may play a significant role in the modulation of maternal-fetal immune response. [ABSTRACT FROM AUTHOR]