Preimplantation Genetic Diagnosis

PGS of aneuploidies by array CGH

PGD by aCGH is based on the technique of array CGH. It allows the study of unbalanced rearrangements in 24 chromosomes. At the same time, the effectiveness of the techniques is improved, such as PGD by means of FISH that only studies alterations in some chromosomes.

The simultaneous study of all the possible aneuploidies leads to sensitively improving the probabilities of success in an IVF cycle. The information related to the rest of the non-implicated chromosomes in the rearrangements is important for two reasons:

  1. The aneuploidy is a very frequent phenomenon in embryos at the preimplantation stage. It is estimated that up to 70% of embryos generated by IVF are aneuploidies.
  2. The interchromosomal effect: there are chromosomes that are not implicated in the translocations and are affected in the offspring.

ADVANTAGES

  • We obtain information on all the chromosomes and the genetic regions distributed in it.
  • A larger capacity to detect unbalanced structural anomalies compared to FISH (up to 20% more abnormal embryos are detected).
  • Results in 24 hours.

LIMITATIONS

  • Haploid and homogeneous polyploidy embryos are not detected (69 XXX, 92XXXX, 92 XXYY). The represent 0.2% of the total of embryos.
  • Deletions and duplications of very small size are not detected.