You might want to consider PGT-A if you are undergoing IVF, especially if you are 35 years old or above as aneuploidy risk increases with age, or if you have had previous pregnancy losses.

PGT-A may help reduce your chance of miscarriage or abnormal pregnancy. It may also reduce the time and cost you experience trying to have a healthy baby, by helping to select the best embryo for transfer. PGT-A can help reduce the risks associated with transferring multiple embryos at once.

PGT-A, like all screening tests, is not 100% accurate. It cannot guarantee you’ll have a chromosomally normal baby. It does not replace the prenatal screening that will be offered to you and all pregnant people. Also keep in mind that most birth defects are not related to missing or extra chromosomes, and some defects are not detectable before implantation or during pregnancy.

PGT-SR stands for pre-implantation genetic testing of structural rearrangements, also known as chromosome translocations. Individuals who are known carriers of a balanced chromosomal translocation may consider PGT-SR.

You might want to consider PGT-M if you would like to prevent passing on a specific genetic disease to your child. This includes X-linked, autosomal recessive and autosomal dominant diseases.

What are X-linked diseases?

We normally have 46 chromosomes in every cell. Chromosomes are the structures in which our DNA, our genes, are stored. An embryo receives 23 chromosomes from the sperm and 23 from the egg. Twenty-two of those are matching pairs called the autosomes. The twenty-third pair are the sex chromosomes and they are most commonly either XX or XY.  X-linked disorders are caused when there is a mutation in a gene on the X chromosome. Examples of X-linked disorders include hemophilia and Duchenne muscular dystrophy.

What are autosomal diseases?

Autosomal diseases are when there is a mutation in a gene on one of the autosomes.

Autosomal dominant diseases are genetic conditions that can occur if only one copy of the gene has a mutation. In cases of autosomal dominant diseases, one parent carries the abnormal gene, and the embryo has a 50% chance of being affected. Examples of autosomal dominant diseases include Marfan syndrome and neurofibromatosis type 1.

Autosomal recessive diseases are genetic conditions that can occur only when an both copies of a gene have a mutation. When an individual has one copy of the gene with a mutation and one without, they are said to be carriers. Typically, being a carrier of a genetic condition does not have an impact on one’s health. When both parents are carriers for the same autosomal recessive disease, the embryo has a 25% chance of being affected. Examples of autosomal recessive diseases include cystic fibrosis and sickle cell anemia.

PGT-M is not 100% accurate. It cannot guarantee you will have an unaffected baby. Because it is not a perfect test, we strongly recommend that all people who get pregnant after doing PGT-M speak with a genetic counsellor about the risks and benefits of amniocentesis.

If you are interested in IVF and PGT-M or PGT-SR or PGT-A, first talk about it with your primary care provider.  They can refer you to Mount Sinai Fertility. After meeting with your Fertility Specialist, you will be referred to meet with a genetic counsellor. They will make sure you are fully informed before making a decision to move forward with the testing.

With PGT-M and PGT-SR we will work with the genetic testing laboratory (also called the reference lab) to ensure that the genetic change can be reliably detected. This process is called case acceptance or probe development and must happen before you begin your IVF cycle.

For you, the patient, the steps will be the same as the IVF process. The difference is what happens in the laboratory when your embryos reach the blastocyst stage: