Using SNP array to identify aneuploidy and segmental imbalance in translocation carriers

Area of Science:

• Genetics
• Reproductive Medicine
• Genomic Technologies

Background:

• Chromosomal translocations, affecting 0.2% of the population, are common structural rearrangements.
• Balanced translocations (Robertsonian, reciprocal) typically lack phenotypic abnormalities but increase reproductive risks like infertility and developmental delays.
• Array-based whole-genome amplification (WGA) technologies, including array CGH and SNP microarrays, enable comprehensive chromosomal screening.

Purpose of the Study:

• To evaluate the clinical application and effectiveness of array-based preimplantation genetic diagnosis (PGD) for carriers of chromosomal translocations.
• To compare the outcomes of different PGD techniques, embryo biopsy stages, and embryo transfer methods.

Main Methods:

• Utilizing array-based WGA technologies like array CGH and SNP microarrays for chromosomal screening in translocation carriers.
• Investigating embryo biopsy techniques, including polar body, cleavage embryo, and blastocyst biopsy.
• Analyzing embryo transfer modes, such as fresh versus frozen embryo transfer.

Main Results:

• Array-based PGD has shown promising transfer pregnancy rates of 45-70% in translocation carriers.
• Blastocyst biopsy is generally recommended over blastomere biopsy to mitigate mosaicism and biopsy-related damage.
• Clinical data is still needed to definitively establish the superiority of SNP-PGD with trophectoderm biopsy and frozen embryo transfer over traditional FISH-PGD with Day 3 biopsy and fresh embryo transfer.

Conclusions:

• Array-based PGD techniques offer a viable approach for assessing chromosomal abnormalities in translocation carriers.
• Optimizing embryo biopsy and transfer strategies is crucial for improving PGD success rates.
• Further clinical validation is required to confirm the most effective combination of PGD technology, biopsy method, and embryo transfer for translocation carriers.