Possible interchromosomal effect in embryos generated by gametes from translocation carriers

Area of Science:

• Reproductive genetics
• Human genetics
• Cytogenetics

Background:

• Balanced translocations in carriers significantly influence abnormal pregnancy rates.
• The specific chromosomes involved dictate the risk of pregnancy complications.

Purpose of the Study:

• To evaluate the efficacy of combining preimplantation genetic diagnosis (PGD) with conventional aneuploidy screening for translocation carriers.
• To assess the potential benefits of this combined approach in identifying chromosomally abnormal embryos.

Main Methods:

• Conducted 43 PGD cycles on 28 carriers of Robertsonian and reciprocal translocations.
• Screened 172 embryos for translocation-specific abnormalities and common aneuploidies (chromosomes 13, 16, 18, 21, 22, XY).
• Investigated 40 embryos from reciprocal translocation carriers for common aneuploidies.

Main Results:

• For Robertsonian translocations, 21% of embryos showed translocation-related abnormalities, 31% common aneuploidies, and 36% both.
• In reciprocal translocations, 65% of abnormalities were translocation-related, 6% common aneuploidies, and 16% both.
• A significant proportion of embryos exhibited abnormalities due to both translocation and non-translocation-related chromosomal issues.

Conclusions:

• An interchromosomal effect appears to contribute to aneuploidy in Robertsonian translocations.
• This increased aneuploidy risk in carriers of Robertsonian translocations poses an additional risk for abnormal pregnancies.
• Combined PGD and aneuploidy screening offers valuable insights for translocation carriers.