Genotyping of human platelet antigen-15 by single closed-tube Tm-shift method

Comparison Between Three Molecular Diagnostics for the Identification of Heterozygous Hemoglobin E

BACKGROUND AND OBJECTIVES

Hemoglobin E is a variant hemoglobin caused due to the base substitution G→A at codon 26 in the β-globin-coding gene that is followed by the alteration of glutamic acid (GAG) to lysine (AAG). Various types of molecular analysis methods such as tetra-primer amplification refractory mutation system (T-ARMS-PCR), Tm-shift real-time polymerase chain reaction (Tm-shift qPCR) and high-resolution melting analysis (HRMA) are commonly used to detect several mutations in the β-globin-coding gene. This study was conducted to compare the detection result of Cd 26 (G→A) mutation in the β-globin-coding gene of heterozygous HbE between the above-mentioned methods.

MATERIALS AND METHODS

DNA samples were isolated from blood archive of heterozygous HbE and analyzed for the detection of the mutation using HRMA and Tm-shift on a real-time PCR instrument, whereas T-ARMS analysis was performed on a conventional PCR equipment. High resolution melt v3.1 software and Bio-Rad CFX Manager software were used to analyze the result of HRMA and Tm-shift qPCR, whereas the T-ARMS-PCR result was analyzed by observing the number and size of DNA bands on gel electrophoresis.

RESULTS

Among 21 samples, the Cd 26 mutation was detected in numbers 18, 19 and 21 by HRMA, Tm-shift qPCR and T-ARMS-PCR. DNA Sequencing confirmed Cd 26 mutation on 5 ambiguous samples and revealed two homozygous mutation.

CONCLUSION

The Cd 26 (G→A) mutation was detected in proportions 100, 91 and 86% by T-ARMS-PCR, Tm-shift qPCR and HRMA, respectively.

Frequency of allotype "b" in human platelet antigen 1 to 29 systems among blood donors in Japan estimated using high-resolution melt analysis

BACKGROUND

Antibodies against human platelet antigens (HPAs) cause thrombocytopenias. It is thus important to know the frequency of "b" allotypes in each HPA system for the diagnosis and treatment of anti-HPA antibody-mediated thrombocytopenia.

STUDY DESIGN AND METHODS

Genomic DNA was extracted from peripheral blood cells obtained from 2170 blood donors in Japan and was subjected to high-resolution melt (HRM) analysis using polymerase chain reaction for each of the HPA genes, using 23 primer pairs. For genotyping, the resulting amplicons were classified based on their HRM curves. In some cases, direct sequence analysis was performed after HRM analysis to determine nucleotide substitutions. In cases where amino acid substitutions were predicted, protein expression levels were examined in a cell line using 293T cells.

RESULTS

The frequencies of each of the HPA-b genotypes were as follows: HPA-1b, 0.4%; HPA-2b, 11.8%; HPA-3b, 41.3%; HPA-4b, 0.8%; HPA-5b, 4.3%; HPA-6b, 1.9%; HPA-15b, 48.8%; HPA-21b, 0.6%; and "b" allotype in the other HPA systems, 0.0%. Twenty-eight variants were found; nine of them were predicted to cause amino acid substitution. However, expression analysis revealed that they did not affect protein expression levels on the cell surface.

CONCLUSION

Nine HPA systems are of primary importance in Japan in potentially triggering thrombocytopenia via the HPA antibodies. Similar studies in other countries or races, together with ours, could provide basic information for clinicians in multiethnic societies.

Tm-Shift Detection of Dog-Derived Ancylostoma ceylanicum and A. caninum

To develop a T_m-shift method for detection of dog-derived Ancylostoma ceylanicum and A. caninum, three sets of primers were designed based on three SNPs (ITS71, ITS197, and ITS296) of their internal transcribed spacer 1 (ITS1) sequences. The detection effect of the T_m-shift was assessed through the stability, sensitivity, accuracy test, and clinical detection. The results showed that these three sets of primers could distinguish accurately between A. ceylanicum and A. caninum. The coefficient of variation in their T_m values on the three SNPs was 0.09% and 0.15% (ITS71), 0.18% and 0.14% (ITS197), and 0.13% and 0.07% (ITS296), respectively. The lowest detectable concentration of standard plasmids for A. ceylanicum and A. caninum was 5.33 × 10⁻⁶ ng/μL and 5.03 × 10⁻⁶ ng/μL. The T_m-shift results of ten DNA samples from the dog-derived hookworms were consistent with their known species. In the clinical detection of 50 fecal samples from stray dogs, the positive rate of hookworm detected by T_m-shift (42%) was significantly higher than that by microscopic examination (34%), and the former can identify the Ancylostoma species. It is concluded that the T_m-shift method is rapid, specific, sensitive, and suitable for the clinical detection and zoonotic risk assessment of the dog-derived hookworm.

Development of T m -shift genotyping method for detection of cat-derived Giardia lamblia

To develop T _m -shift genotyping method for detection of cat-derived Giardia lamblia, two sets of primers with two GC-rich tails of unequal length attached to their 5'-end were designed according to two SNPs (BG434 and BG170) of β-giardin (bg) gene, and specific PCR products were identified by inspection of a melting curve on real-time PCR thermocycler. A series of experiments on the stability, sensitivity, and accuracy of T _m -shift method was tested, and clinical samples were also detected. The results showed that two sets of primers based on SNP could distinguish accurately between assemblages A and F. Coefficient of variation of T _m values of assemblage A and F was 0.14 and 0.07% in BG434 and 0.10 and 0.11% in BG170, respectively. The lowest detection concentration was 4.52 × 10^-5 and 4.88 × 10^-5 ng/μL samples of assemblage A and F standard plasmids. The T _m -shift genotyping results of ten DNA samples from the cat-derived G. lamblia were consistent with their known genotypes. The detection rate of clinical samples by T _m -shift was higher than that by microscopy, and their genotyping results were in complete accordance with sequencing results. It is concluded that the T _m -shift genotyping method is rapid, specific, and sensitive and may provide a new technological mean for molecular detection and epidemiological investigation of the cat-derived G. lamblia.

Advances in alloimmune thrombocytopenia: perspectives on current concepts of human platelet antigens, antibody detection strategies, and genotyping

Alloimmunisation to platelets leads to the production of antibodies against platelet antigens and consequently to thrombocytopenia. Numerous molecules located on the platelet surface are antigenic and induce immune-mediated platelet destruction with symptoms that can be serious. Human platelet antigens (HPA) cause thrombocytopenias, such as neonatal alloimmune thrombocytopenia, post-transfusion purpura, and platelet transfusion refractoriness. Thirty-four HPA are classified into 28 systems. Assays to identify HPA and anti-HPA antibodies are critically important for preventing and treating thrombocytopenia caused by anti-HPA antibodies. Significant progress in furthering our understanding of HPA has been made in the last decade: new HPA have been discovered, antibody-detection methods have improved, and new genotyping methods have been developed. We review these advances and discuss issues that remain to be resolved as well as future prospects for preventing and treating immune thrombocytopenia.

An association study between genetic polymorphism in the interleukin-6 receptor gene and coronary heart disease

The goal of our study is to test the association of IL6R rs7529229 polymorphism with CHD through a case-control study in Han Chinese population and a meta-analysis. Our result showed there is a lack of association between IL6R rs7529229 polymorphism and CHD on both genotype and allele levels in Han Chinese (P > 0.05). However, a meta-analysis among 11678 cases and 12861 controls showed that rs7529229-C allele was significantly associated with a decreased risk of CHD, especially in Europeans (P < 0.0001, odds ratio = 0.93, 95% confidential interval = 0.89–0.96). Since there is significant difference among different populations, further studies are warranted to test the contribution of rs7529229 to CHD in other ethnic populations.