Comprehensive chromosomal and mitochondrial copy number profiling in human IVF embryos

Area of Science:

• Genomics
• Reproductive Biology
• Mitochondrial DNA Analysis

Background:

• Single cell whole genome sequencing is crucial for analyzing genetic heterogeneity and trace DNA, particularly in human embryos.
• The mitochondrial genome is often overlooked in single cell analyses despite its importance in eukaryotic cells.
• Existing methods may not simultaneously assess both chromosomal and mitochondrial DNA at the single-cell level.

Purpose of the Study:

• To evaluate a novel single cell whole genome amplification method, MALBAC-NGS, for simultaneous chromosomal and mitochondrial genome analysis.
• To investigate the relationship between maternal age, embryo implantation, and mitochondrial copy number.
• To explore the potential of MALBAC-NGS for advanced pre-implantation genetic screening.

Main Methods:

• Utilized multiple annealing and looping based amplification cycles coupled with next-generation sequencing (MALBAC-NGS) for single cell analysis.
• Validated the platform through technical and biological replicates.
• Analyzed chromosomal and mitochondrial copy number in 399 in-vitro fertilized embryos from 81 couples.

Main Results:

• A significant positive correlation was found between maternal age and increased mitochondrial quantity (β = 0.176, P = 0.001) after adjusting for cell type.
• Successfully implanted embryos showed a trend towards lower mitochondrial numbers, though this was not statistically significant.
• The MALBAC-NGS platform demonstrated reliability for simultaneous genomic and mitochondrial DNA analysis.

Conclusions:

• MALBAC-NGS is a viable method for comprehensive single-cell genome analysis, including mitochondrial DNA.
• Maternal age is a significant factor influencing mitochondrial quantity in early human embryos.
• This technology holds promise for enhancing pre-implantation genetic screening by assessing both chromosomal and mitochondrial status.