We inferred the source of the error using two approaches:
1) Sex chr composition (XXX/XXY/XYY etc)
2) 55 embryos with parental data
Findings:
1) Almost all triploid errors are maternal, with ~1/3 from meiosis I and ~2/3 from meiosis II
2) Almost all haploid errors are paternal
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1) Sex chr composition (XXX/XXY/XYY etc)
2) 55 embryos with parental data
Findings:
1) Almost all triploid errors are maternal, with ~1/3 from meiosis I and ~2/3 from meiosis II
2) Almost all haploid errors are paternal
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Comments
We found less crossovers than expected. Further, embryos with less crossovers had more additional aneuploidies in specific chrs (on top of the triploidy).
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These embryos had both maternal chrs genome-wide.
(Except chrs with an additional aneuploidy; see figure for SNP array validation of one such embryo.)
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Naturally, these embryos have high levels of homozygosity.
How the paternal genome disappeared is unknown.
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Finally, ploidy aberrations tends to cluster in families: six couples had three affected embryos (four with female age<35), unexpected by chance, suggesting a genetic basis.
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Identifying and understanding these errors will contribute to explaining meiosis and infertility.
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