Long Fragment Polymerase Chain Reaction

Comprehensive Annotation of Complete ABO Alleles and Resolution of ABO Variants by an Improved Full-Length ABO Haplotype Sequencing

BACKGROUND

Full-length ABO haplotype sequencing is crucial for accurate genotyping, reference gene annotation, and molecular mechanism analysis of its variants. However, there is currently a deficiency of comprehensive annotation for full-length ABO haplotypes, spanning from the 5' untranslated region (UTR) to the 3' UTR.

METHODS

Two sets of specimens (79 random blood donors and 47 ABO variants) were tested. The full-length ABO gene spanning the 5' UTR to the 3' UTR was amplified using an improved one-step ultra-long-range PCR with a pair of PCR suppression primers. A single-molecule real-time library was constructed, and ABO haplotype sequencing was performed. Data analysis including basecalling, aligning, variant calling, clustering, and variant annotation were performed.

RESULTS

The amplicon measured 26.1 kb without splicing, representing the most complete ABO gene reported to date. The complete ABO haplotype sequence was obtained via long-read sequencing. The comprehensive ABO reference alleles were obtained and the ABO sequence patterns within each allele in a Chinese population were further classified. The full-length ABO gene haplotype analysis technique effectively resolved ABO variants with structural variations (SVs), including large fragment deletions, inversions, recombination, and chimeras.

CONCLUSIONS

Full-length ABO haplotype sequencing filled a gap that was missing with respect to the 3' UTR sequences of ABO alleles and can advance blood group genomic analysis, aiding in ABO gene function analysis, evolutionary studies, and the resolution of ABO variants.

A novel in silico molecular tool for comprehensive differentiation of Mycobacterium species

The Identification of various mycobacterial species is critical for understanding their pathogenicity and epidemiology. Despite the existence of several established methods for identifying mycobacterial species, each of these methods has several significant limitations, including high costs, substantial time demands, and a restricted ability to detect a wide range of recoverable species. This study presents an in silico method using restriction fragment length polymorphism (RFLP) to differentially identify 75 clinically important mycobacterial species.The present investigation employed specific primer combinations to identify and generate a distinct hypervariable sequence across the ribosomal RNA gene. This unique sequence using appropriate restriction enzyme digestion followed by gel electrophoresis enabled the creation of highly precise and distinct patterns or profiles for each of the 75 medically relevant Mycobacterium species, including members of closely related Mycobacterium complex groups. This approach can quickly and reliably identify mycobacterial species, allowing for more timely treatment decisions and contributing to beneficial epidemiological investigations.

A Novel Bead-Capture Nanopore Sequencing Method for Large Structural Rearrangement Detection in Cancer

Rapid, cost-effective genomic stratification of structural rearrangements in cancer is often of vital importance when determining treatment; however, existing diagnostic cytogenetic and molecular testing fails to deliver the required speed when deployed at scale. Next-generation sequencing-based methods are widely used, but these can lack sensitivity and require batching of samples to be cost-effective, with long turnaround times. Here we present a novel method for rearrangement detection from genomic DNA based on third-generation long-read sequencing that overcomes these time and cost issues. The utility of this approach for the genomic stratification of patients with acute myeloid leukemia is shown based on detection of four of the most prevalent structural rearrangements. The method not only determines the precise genomic breakpoint for each expected rearrangement but also discovers and validates novel translocations in one-third of the tested samples, 80% of which involve known oncogenes. This method may prove to be a powerful tool for the diagnosis, genomic stratification, and characterization of cancers.

STI PCR: An efficient method for amplification and de novo synthesis of long DNA sequences

Despite continuous improvements, it is difficult to efficiently amplify large sequences from complex templates using current PCR methods. Here, we developed a suppression thermo-interlaced (STI) PCR method for the efficient and specific amplification of long DNA sequences from genomes and synthetic DNA pools. This method uses site-specific primers containing a common 5' tag to generate a stem-loop structure, thereby repressing the amplification of smaller non-specific products through PCR suppression (PS). However, large target products are less affected by PS and show enhanced amplification when the competitive amplification of non-specific products is suppressed. Furthermore, this method uses nested thermo-interlaced cycling with varied temperatures to optimize strand extension of long sequences with an uneven GC distribution. The combination of these two factors in STI PCR produces a multiplier effect, markedly increasing specificity and amplification capacity. We also developed a webtool, calGC, for analyzing the GC distribution of target DNA sequences and selecting suitable thermo-cycling programs for STI PCR. Using this method, we stably amplified very long genomic fragments (up to 38 kb) from plants and human and greatly increased the length of de novo DNA synthesis, which has many applications such as cloning, expression, and targeted genomic sequencing. Our method greatly extends PCR capacity and has great potential for use in biological fields.