Clinical Application and Advantage Analysis of Combinatorial Probe-Anchor Synthesis Sequencing in Preimplantation Genetic Testing for Chromosomal Aneuploidy

Technical Principles and Testing Workflow

The Preimplantation Genetic Testing for Chromosome Aneuploidy Kit (combinatorial probe-anchor synthesis sequencing method) is based on a high-throughput sequencing platform. It involves whole-genome amplification of a small number of cells obtained from embryo biopsy, followed by capture and anchoring of target chromosomal regions using specific probes, and then acquisition of sequence information through combinatorial sequencing. This method enables simultaneous screening for numerical abnormalities of all 24 chromosomes, thereby identifying common aneuploidies (such as trisomy 21, trisomy 18, trisomy 13, etc.) as well as segmental duplications or deletions. In terms of operational workflow, it generally includes steps such as embryo biopsy, whole-genome amplification, library construction, probe hybridization capture, sequencing, and bioinformatics analysis. Laboratories must strictly follow the quality control parameters specified in the kit instructions, such as library concentration, sequencing data volume, and alignment rate, to ensure the reliability of results.

Clinical Application Value and Precautions

In the field of assisted reproduction, this kit is primarily used for chromosome aneuploidy screening of blastocysts after in vitro fertilization, helping to select embryos with normal chromosome numbers for transfer, thereby improving clinical pregnancy rates, reducing miscarriage rates, and decreasing the risk of birth defects. Clinical studies have shown that after adopting this technology, the live birth rate per single transfer in specific age groups has significantly improved, but the specific effects vary depending on individual patient factors (such as age, ovarian reserve function, and embryo quality). It should be emphasized that this test only targets numerical chromosome abnormalities and cannot detect chromosomal structural rearrangements, monogenic diseases, or polygenic diseases, and there is a very low proportion of possible missed detection of mosaicism. When explaining results to patients, physicians should avoid absolute promises such as "absolutely normal" or "100% success," and it is recommended to make comprehensive decisions in combination with embryo morphological scoring, genetic counseling, and ethical considerations.

Comparison with Other Screening Methods

Compared with traditional technologies such as fluorescence in situ hybridization (FISH) and array comparative genomic hybridization (aCGH), the combinatorial probe-anchor synthesis sequencing method has higher throughput and resolution. FISH typically can only detect 5-9 chromosomes, whereas this kit can cover all chromosomes and can identify abnormalities in small segments. Compared with aCGH, the sequencing method has a lower starting DNA requirement (as low as 5-10 cells), making it more suitable for embryo biopsy samples. In addition, this technology does not rely on known polymorphic loci in advance and can simultaneously provide SNP information for parental origin analysis, which helps exclude maternal contamination. However, this method has high requirements for laboratory hardware, reagents, and software analysis capabilities, requiring professional personnel to perform operations and data interpretation to avoid false positives or false negatives caused by amplification bias or sequencing errors.

Quality Control and Standardization Recommendations

To ensure the accuracy and reproducibility of test results, laboratories should establish a comprehensive internal quality control system. It is recommended to set up positive controls (known aneuploid samples) and negative controls (normal diploid samples) for each batch of testing, and monitor key indicators such as the number of effective sequencing reads, alignment rate, GC content distribution, and the detection limit of chromosomal copy number variations. The storage and use of the kit should strictly follow temperature requirements, avoiding repeated freeze-thaw cycles. At the same time, when interpreting results, it is necessary to combine the thresholds set by bioinformatics algorithms; for samples with borderline values, repeat testing or validation with other technologies is recommended. Practitioners should regularly participate in external quality assessment activities and pay attention to the registration review requirements of the National Medical Products Administration (NMPA) for such kits. Currently, similar products from multiple domestic manufacturers have obtained Class III medical device registration certificates, and their performance indicators must meet general requirements such as sensitivity not less than 99% and specificity not less than 98%.