News Releases & Research Results Spontaneous correction of the chromosome number that enables fetal birth occurs exclusively during the first few days after fertilization ―Chromosome number modification required for embryo maturation is controlled by biological clock rather than the number of cells―

Results of research led by Researcher Yoshida and Director Fukami of Department of Molecular Endocrinology, National Center for Child Health and Development.

• Abnormalities in the chromosome number (47 or 45 with 46 being normal) were found to be spontaneously corrected (i.e. aneuploid rescue) in human embryo cells exclusively during the first few days after fertilization
• In the cellular embryo receiving aneuploid rescue, a modification named X chromosome inactivation* was demonstrated to be initiated at the same timing as the normal cellular embryo.
  * Activity inhibition of either paternal (n=23) or maternal (n=23) X chromosome in the cells
• It is expected to support process elucidation of human embryo maturation as well as understanding of pathogenic mechanism of aberrant chromosome.

This research and development was supported by AMED`s Practical Research Project for Rare/Intractable Diseases.

Yoshida T., et al. Aneuploid rescue precedes X chromosome inactivation and increases the incidence of its skewness by reducing the size of the embryonic progenitor cell, Human Reproduction, 2019
DOI：10.1093/humrep/dez117