What is a mosaic?

Question
Hello doctor,
I did IVF but got 3 embryos, all of which are mosaic embryos. The doctor asked me what is a mosaic embryo? Thank you doctor.
Anonymous customer
Answer
Answered by Master, Doctor Trinh Thi Thanh Huyen - Department of Obstetrics and Gynecology, Vinmec Hai Phong International General Hospital.
Hello,
With the question “What is a mosaic? ”, the doctor would like to answer as follows:
Mosaic embryo is defined as when two or more blastomeres with different genotypes are present in the same embryo. It is formed by the failure of meiosis during division of the embryo. In simpler terms, mosaic embryos are embryos where the chromosomal abnormality occurs in only one group of cells, not all cells. That is, if there is a gene for a disease, a person carrying the mosaic gene will have milder symptoms than typical symptoms of that disease.
Because the current literature has clearly shown some cases of patients who were transferred mosaic embryos but still developed into normal fetuses and delivered healthy babies, the rate of pregnancy progressing is similar with different degrees of mosaicism , so if the patient is completely without diploid embryos during this cycle and is not able to perform PGS (chromosomal testing) for further cycles, then mosaic embryos can be used. But there needs to be a consensus between the patient and the treatment center. Because mosaic embryos still have some cells containing the wrong number of chromosomes, they have a lower implantation potential and an increased risk of miscarriage compared with normal embryos.
In this case, you should directly see a doctor who works in fertility support and embryology for more in-depth advice.
If you still have questions about mosaic embryos, you can go to a hospital under Vinmec Health System for further examination and advice. Thank you for trusting and sending questions to Vinmec. Wishing you lots of health.
Best regards!