Genetic testing improves IVF success

In vitro fertilization has helped many desiring couples achieve pregnancy, but successful outcomes aren’t always guaranteed. 

It’s important to know that most failed IVF cycles are due to random genetic abnormalities in the embryo(s).

Inefficiencies in reproduction

Unfortunately, human reproduction is fairly inefficient, and the older we get, it becomes even more inefficient. 

Since the inception of IVF in the early 1980’s, we’ve worked diligently to combat these inefficiencies and, there have been many advances that have led to significantly higher pregnancy rates. Arguably, none have been as groundbreaking as preimplantation genetic testing. 

Preimplantation genetic testing comes in two forms: 

• Preimplantation genetic testing for aneuploidy (PGT-A) 
• Preimplantation genetic testing for single gene mutation (PGT-M)

IVF and genetic testing

With either procedure, a couple goes through a standard IVF cycle, in which eggs are retrieved and sperm is obtained. Embryos are created and then cultured to the blastocyst stage. That process takes five days. It’s important to note that not all fertilized embryos develop to blastocysts.

On the fifth day, a trophectoderm biopsy is performed. A few cells are removed from the portion of the embryo destined to become placenta. The cells are sent for genetic testing, and the embryos are frozen. Once a genetic report is generated, a frozen embryo transfer can take place.

How preimplantation genetic testing helps with success

PGT-A is used when a couple wants to screen their embryos for random genetic events or the genetic errors that can cause IVF to fail. These are genetic problems with the embryo that don’t have to do with the parents’ age and are believed to be the primary reason an IVF cycle doesn’t work. 

If you can determine which embryos are genetically normal (known as euploid embryos), a couple is able to increase their odds of success and minimize their chances of miscarriage. Although success rates will vary from patient to patient and clinic to clinic, pregnancy rates generally increase by 10-20% after PGT-A. Miscarriages can still occur even though the embryos are prescreened.
 

Preimplantation genetic testing and screening for errors

Genetic testing can do more than pinpoint these random genetic errors. We can perform PGT-M for specific genetic mutations, such as cystic fibrosis or spinal muscular atrophy. These are abnormalities in an individual’s DNA that predispose his or her children to a specific disease. 

These disease mutations can be dominant, in which a single gene carried by one parent results in clinical disease. Or, they can be recessive, in which both parents have to carry the genetic mutation and pass it on to their child. 

In the case of a dominant inheritance pattern, there’s a 50% chance the offspring will have clinical disease. With a recessive pattern, there’s a 25% chance the offspring will have clinical disease while half will be carriers. 

PGT-M should be considered when an individual has been diagnosed with a hereditary disease, had a child diagnosed with a hereditary disease, has family members with a hereditary disease or both partners have been diagnosed as carriers of a genetic disorder. 

Preimplantation genetic testing for structural rearrangements (PGT-SR) checks for chromosomal translocation when one parent has been identified as a carrier of a chromosomal translocation.

Screening parents first

How can you know if you and your partner are both disease carriers? There are genetic screening panels commercially available and can be ordered by your provider. At Methodist Hospital Reproductive Health Specialists, all our patients are offered carrier screening at their first visit. Carrier testing is optional but encouraged to help ensure the best outcome possible for your child(ren).