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Christian S Ottolini The Evewell, London, UK & University of - - PowerPoint PPT Presentation
Christian S Ottolini The Evewell, London, UK & University of - - PowerPoint PPT Presentation
Mosaicism, cleavage stage anomalies and developmental arrest in vitro Christian S Ottolini The Evewell, London, UK & University of Kent, Canterbury, UK Human in in vit itro preim impla lantation embry ryo develo lopment and genetics
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Methodology
- Clinical PGT cases
- Serial PB1 and PB2 biopsy
- Time-lapse monitoring
- Blastocyst culture (Single step)
- Trophectoderm biopsy and embryo vitrification
- Total or partial disaggregation of arrested embryos into single cells
(Day 5 or Day 6 of embryo development)
- Sample and patient’s gDNA genome wide SNP genotyping
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Meiomapping Karyomapping
Ottolini et al (2015) Nature Genetics
Chromosome Profilin ing
- Accurately establish a baseline of
maternal meiotic aneuploidy
- Chromosome fingerprinting with
unique pattern of paternal haplotypes
- Single cell chromosome
fingerprints consistent between cells and with Meiomap
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Profile of dis isagg ggregated embry ryo
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Partitioning chromosomes on a tripolar spindle
- Random attachment of
chromosomes to one of three axes
- Normal bi-parental diplody
- Maternal and paternal
monosomy
- Nullisomy
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Profile of dis isagg ggregated embry ryo
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Time-lapse – Cleavage patterns
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Single cell results
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Daughter cells Sub-diploid (nullisomy) Near-diploid (no nullisomy) Diploid Tri-polar mitosis Other abnormal mitotic events
Abnormal cleavage: Chromosome loss in daughter cells
- Biology is seldom conforms
- Several other patterns of abnormal cleavage
- Cells with no nullisomy would presumably behave
like meiotic aneuploidy
- Abnormal divisions can still give rise to normal
cells
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- Most failure of human in vitro fertilisation (IVF) has an underlying genetic basis.
- Catastrophic genomic events in early cleavage result in intercellular partitioning
- f the chromosomes (genome loss).
- Affected (sub-diploid) cells can continue to divide but are unable to develop,
post embryonic genome activation, and form into a blastocyst structure.
- Cleavage stage embryo transfer will not overcome this problem.
- Clinical PGT-A and mosaicism!
- Understanding the issue could lead to treatments that would have the potential
to double current IVF success rates.
Findings & Clinical implications
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Mr Michael Summers Professor Alan Handyside Samantha Neumann Dr Julija Gorodeckaja Professor Darren Griffin @The Bridge Centre @University of Kent @CooperGenomics Dr John Kitchen Dr Leoni Xanthopoulou Dr Tony Gordon and my team @