Study of Abnormally Fertilized Embryos

On fertilization, following the conventional ICSI/IVF procedure, samples from cumulus cells (obtained during the routine oocyte denudation process) and surplus sperm cells present in seminal plasma will be retrieved. These samples will be stored frozen at -20°C until they are sent to Igenomix. There, they will be used to perform the genetic analysis required to achieve the study's objectives, provided the patient consents to participate. If the patient ultimately chooses not to participate, these samples will be destroyed. Parents may be asked to provide a saliva sample for the same purpose in cases where obtaining the samples during fertilization was not possible or if the collected samples were unsuitable for processing in the laboratory. The saliva sample may be collected at the clinic during one of the scheduled visits for reproductive treatment or, alternatively, by the parents at home using a kit provided by the clinic.

On day 3 of development, assisted hatching will be performed to facilitate biopsy at the blastocyst stage. Each embryo will be biopsied in the laboratory using conventional trophectoderm (TE) biopsy techniques on day +5, +6, or +7 of development, depending on when they reach the appropriate blastocyst stage. After biopsy, blastocyst will be vitrified following the clinical routine protocol and store until the genetic results are available. The biopsy samples will be placed in a PCR tube labeled with its corresponding study-specific code and stored in a cold rack at 4°C before being transferred to a freezer at -20°C. Finally, the samples will be sent to the Igenomix for preimplantation genetic testing for aneuploidy.

After obtaining the PGT-A results, any embryo not genetically confirmed as euploid and without ploidy abnormalities will be thawed, washed, and cultured for rebiopsy. A complementary analysis using next-generation sequencing (NGS) techniques will be performed to confirm the diagnosis and determine the origin of the abnormalities. For this additional analysis, in addition to the new biopsies, the individual culture medium of each embryo will be aspirated after an incubation period of 8 to 24 hours. The collected medium will be placed in PCR tubes and stored in a freezer at -20°C before being sent to the laboratory. Regardless the result of these complementary analysis, no rebiopsied blastocyst will be considered for clinical purposes.