Preimplantation genetic testing-mutation or Preimplantation genetic testing-structural arrangement (PGT-M or PGT-SR) is a similar procedure like PGT-A. The only difference is PGT-M or PGT-SR are used for the couples who carry genetic defects or chromosomal abnormalities. Embryos will develop in the incubator until they reach blastocyst stage (typically after 5-7 days), then 5-7 cells from trophectoderm (placenta in the future) are removed and tested for genetic defects or chromosomal abnormalities within embryos. This procedure serves to prevent certain genetic diseases or disorders from being passed on to the child.