We have sequenced exons 2, 3 and 4 of MIC‐A in 23 homozygous cell lines, 22 families and 54 unrelated individuals. This has led to the definition of seven polymorphic positions in exon 2, 13 in exon 3 and 12 in exon 4, yielding a total of 33 different MIC‐A allelic specificities, of which 16 have not been described before. The newly defined sequences and those of the alleles defined before were entered into a database of the SCORE program (Helmberg et al., 1998, Tissue Antigens, 51, 587) for comprehensive genotyping analysis. In the tested sample, only one genotype present in two individuals gave rise to an ambiguous genotype. If all possible combinations of the 33 alleles are considered, 10 of 636 combinations are ambiguous. The MIC‐A exon 2, 3 and 4 polymorphism is characterized by diallelic single base exchanges and by a considerable degree of exon shuffling. The majority of heterozygote positions identified are non‐synonymous, i.e. five of seven in exon 2, 13 of 13 in exon 3 and eight of 12 in exon 4, suggesting an important function for the MIC‐A polymorphism.
Background and aimsMHC class I polypeptide-related chain A (MICA) molecule is induced in response to viral infection, various types of stress, such as endoplasmic reticulum stress, and ischemia or/and reperfusion, by which MICA was shed from the cell surface into the extracellular domain, generating a soluble form (sMICA). In the present study, we designed to investigate the serum sMICA level in patients with AMI and determine whether sMICA could be an early biomarker for diagnosis of AMI.MethodsThere were 103 patients who presented with first-time AMI that was assessed after the incident. The control group consisted of 103 healthy volunteers. Serum levels of sMICA and Troponin T were detected by the specific ELISA kits.ResultsSerum levels of sMICA reach the peaks [(1.34 ± .18 and 1.72 ± .20)n/l] at 6–12 h and serum levels of cTnT reach the peaks [(1.16 ± .28 and 1.14 ± .34)n/l] at 12–24 h. Both of them were significantly higher than the healthy controls [(.168 ± .014) n/l, p = .000] for sMICA and [(.13 ± .06) n/l, p = .000] for Troponin T (cTnT). sMICA is more sensitive in the early diagnosis of AMI than cTnT. The combined ROC analysis revealed an AUC value of .78 (95 % CI .69–.83) in discriminating AMI patients from healthy controls.ConclusionsWe have detected high levels of sMICA in patients with AMI. Elevated serum sMICA may be a novel biomarker for the early detection of myocardial injury in humans.
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