The study of the spread of reciprocal aneuploidies on preimplantation development using molecular karyotyping of extracellular blastocyst DNA

Actuality: A comparative analysis of the molecular karyotypes of extracellular DNA in intracavitary fluid, inner cell mass and trophectoderm allows registering the phenomenon of reciprocal aneuploidies. This makes it possible to determine the origin of numerical chromosome abnormalities and suggest mechanisms of their occurrence related to post-zygotic chromosome segregation errors. Objective: Evaluation of the frequency of reciprocal aneuploidy in human embryos at the blastocyst stage. Materials and Methods: CGH-analysis of 14 human embryos (day 5) with separation to inner cell mass, trophectoderm and intracavitary fluid. Results: By comparing the molecular karyotypes of DNA from blastocoel fluid, inner cell mass and trophectoderm was found that 64% of embryos had from 1 to 3 reciprocal aneuploidies (9/14). Reciprocal anomalies were formed involving chromosomes 19 (33%), 16 (27%), 17, 21 and 22 (13%). The frequency of reciprocal aneuploidies based on a pair of homologous chromosomes, obtained on the basis of comparative analysis of the molecular karyotype of extracellular DNA, the inner cell mass and trophectoderm was 24% (16/67). The frequency of reciprocal aneuploidies in a comparative analysis of extracellular DNA and the inner cell mass was 21% (14/67), extracellular DNA and trophectoderm - 3% (2/67), inner cell mass and trophectoderm - 10% (7/67). Conclusions: Using of extracellular DNA from the cavity of the blastocyst as a source of additional information about the chromosomal constitution of embryo can increase the probability of detecting of reciprocal aneuploidy by 56%. These anomalies reflect an intensity of mitotic chromosome segregation errors.

внеклеточная ДНК, хромосомный мозаицизм, внутриполостная жидкость бластоцисты, внутренняя клеточная масса, трофэктодерма, реципрокные анеуплоидии, extracellular DNA, chromosomal mosaicism, intracavitary fluid, inner cell mass, trophectoderm, reciprocal aneuploidy

1. Palini S, Galluzzi L, De Stefani S et al. Genomic DNA in human blastocoele fluid. Reprod. Biomed. Online. 2013; 26(6): 603-610.

2. Chow JF, Yeung WS, Lau EY et al. Array comparative genomic hybridization analyses of all blastomeres of a cohort of embryos from young IVF patients revealed significant contribution of mitotic errors to embryo mosaicism at the cleavage stage. Reprod. Biol. Endocrinol. 2014; 12(1): 105.

3. Lebedev I Mosaic aneuploidy in early fetal losses. Cytogenetic and genome research. 2011; 133(2-4): 169-183.

4. Fragouli E, Alfarawati S, Spath K et al. The origin and impact of embryonic aneuploidy. Human genetics. 2013; 132(9): 1001-1013.

5. Kalousek DK Confined placental mosaicism and uniparental disomy. Funct. Dev. Morph. 1994; 4(2): 93-98.

6. Gianaroli L, Magli MC, Pomante A et al. Blastocentesis: a source of DNA for preimplantation genetic testing. Results from a pilot study. Fertil. Steril. 2014; 102(6): 1692-1699.

7. Tobler KJ, Zhao Y, Ross R et al. Blastocoel fluid from differentiated blastocysts harbors embryonic genomic material capable of a whole-genome deoxyribonucleic acid amplification and comprehensive chromosome microarray analysis. Fertil. Steril. 2015; 104(2): 418-425.