Rapid genotyping of HLA-B27 among Korean population by real-time PCR melting curve analysis

High-Throughput and Automated Detection of HLA-B*27 Using the LabTurboTM AIO System

The adoption of an automated system can decrease the hands-on time requirements in a clinical laboratory setting. For the detection of HLA-B*27, implementing a high-throughput and fully automated system has several advantages over using manual methods. Therefore, this study aimed to evaluate automation efficiency for the detection of HLA-B*27. Peripheral blood samples were obtained from 50 participants, and DNA was isolated from these samples. A Pharmigene PG27 detection kit was used for the qualitative detection of HLA-B*27. The performances of the semi-automated and fully automated LabTurbo^TM AIO systems in the detection of HLA-B*27 were compared. The mean absorbance (optical density) values for the Maelstrom^TM 8 and LabTurbo^TM AIO systems were found to be 1.88 and 1.9, respectively. The housekeeping gene was amplified and quantified using a real-time PCR assay across all DNA extracts to check the quality of the extracted human DNA. The results were expressed as the cycle threshold (Ct) values for all DNA extracts from both platforms. The mean Ct values for the Roche Cobas z480 and LabTurbo^TM AIO systems were found to be 22.7 and 20.4, respectively. This study demonstrated that the semi-automated method and the LabTurbo^TM AIO system yield consistent results for the detection of HLA-B*27. However, compared to the semi-automated method, the LabTurbo^TM AIO system provides standardized procedures, avoids manual handling, and improves turnaround time.

Rapid and Reliable One-Step ABO Genotyping Using Direct Real-Time Allele-Specific PCR and Melting Curve Analysis Without DNA Preparation

ABO genotyping is a molecular diagnostic technique important for transfusion and transplantation in medicine, and human identification in forensic science. Because ABO genotyping are labor intensive and time consuming, the genotyping cannot be firstly used to resolve the serological ABO discrepancy in blood bank. For rapid one-step ABO genotyping, we developed direct, real-time, allele-specific polymerase chain reaction (PCR), and melting curve analysis (DRAM assay) without DNA preparation. In DRAM assay, we used a special PCR buffer for direct PCR, a rapid RBC lysis buffer, white blood cells as template without DNA preparation, allele-specific primers for discriminating three ABO alleles (261G/del, 796C/A, and 803G/C), and melting curve analysis as a detection method. There was 100% concordance among the results of ABO genotyping by the DRAM assay, serologic typing, PCR-RFLP and PCR-direct sequencing of 96 venous blood samples. We were able to reduce the number of manual steps to three and the hands-on time to 12 min, compared to seven steps and approximately 40 min for conventional ABO genotyping using allele-specific PCR with purified DNA and agarose gel electrophoresis. We have established and validated the DRAM assay for rapid and reliable one-step ABO genotyping in a closed system. The DRAM assay with an appropriate number of allele-specific primers could help in resolving ABO discrepancies and should be valuable in clinical laboratory and blood bank.

Novel Approaches and Technologies in Molecular HLA Typing

The invention of the Polymerase Chain Reaction (PCR) has revolutionized molecular biology enabling gene isolation and characterization in hours rather than days. Scientists working in transplant diagnostics have proven to be pioneers in adapting this molecular technique to the clinical needs of histocompatibility testing. This chapter describes a number of novel genotyping technologies which have been used to address the challenges posed by genetic diversity seen in the extensive polymorphism in HLA genes. These novel approaches include single-stranded and duplex conformational analyses, real-time PCR, microarray hybridization, RNA-based sequencing, and the present day Next Generation Sequencing. The chapter concludes with a brief look at a possible next, Next Generation Sequencing system.