Our Tests

Preimplantation Genetic Diagnosis (PGD) for Single Gene Disorders

What are Single Gene Disorders?

Single gene disorders are genetic conditions caused by an alteration (mutation) in a specific gene. Single gene disorders are often hereditary (run in families), and therefore, individuals with a family history of a single gene disorder may be at risk for passing the condition onto their children. Examples of single gene disorders include cystic fibrosis, sickle-cell anemia, Tay-Sachs disease, Duchenne muscular dystrophy, Fragile X syndrome and spinal muscular atrophy (SMA).

What is PGD for single gene disorders?

PGD is used to identified embryos that are predicted to be affected with a genetic disease and those that are not. Currently, PGD is the only way to determine whether an embryo is predicted to be affected with a genetic condition prior to achieving pregnancy. PGD has been utilized by many couples wishing to greatly reduce their risk of having a child with a genetic disorder as well as the possibility of being faced with a difficult decision about the outcome of a pregnancy following abnormal prenatal test results.

RGI can perform PGD for essentially any single gene disorder for which the mutation is known, including very rare conditions. The list of single gene disorders for which RGI has previously performed testing can be found here. It should be noted that RGI is always adding to this list. If the disease for which you are interesting in pursuing PGD is not listed, we are happy to review your genetic reports to determine if PGD is feasible.

RGI now offers discounted fees for certain single gene disorders.

How does RGI test for single gene disorders?

Testing a single cell from an embryo is very different than testing a child or adult for a genetic condition. Due to the limited amount of DNA that is available in a single cell, an individualized testing system ("PGD set-up") is developed for each couple before they begin their IVF cycle. Creating the PGD set-up requires a DNA sample from each partner and may require additional DNA samples from family members. Our genetic counselors will inform you of the samples that would be required for your case, as well as the cost and time required for RGI to complete the PGD set-up.

Once the set-up is completed, PGD for single gene disorders can be performed by analysis of polar bodies, blastomeres, and/or blastocyst/trophectoderm. The cells that are biopsied are analyzed using a technique called polymerase chain reaction (PCR). RGI also utilizes DNA "linked markers" (a method of DNA fingerprinting), to optimize the accuracy of PGD results. RGI's genetic counselors will work with you and your physician to determine the optimal testing strategy for your case. If indicated, we can also perform testing for more than one single gene disorder and/or a chromosomal rearrangement. Intracytoplasmic sperm injection (ICSI) is required when PGD is performed for single gene disorders. ICSI greatly reduces the risk of sperm contamination of the cells tested. The optimal accuracy of PGD for a single gene disorder is 98%. The accuracy of the testing may vary depending upon the genetic condition, and the number of unique linked markers for the family. In addition, the accuracy may vary from embryo to embryo within a given cycle.

Can RGI add PGS to single gene PGD?

Additional PGS reduces the chance of failed implantation or an early miscarriage, or of having a child with a chromosomal abnormality (which often causes birth defects and intellectual disabilities). This will increase the chance of a healthy and successful pregnancy after an IVF/PGD cycle. This testing can be performed on the same biopsy sample.