Prevent the transmission of single gene disorders in a family and achieve a healthy pregnancy
1. Introduction. What is it?
Preimplantation genetic diagnosis (PGD) for single gene disorders is a powerful genetic test that may be performed during IVF treatment to screen embryos that are at risk to develop a serious genetic disorder. PGD is performed on a small embryo biopsy and identifies which embryos are not at increased risk of developing the disease. The goal of PGD testing is to help couples build a healthy family. PGD is done before the pregnancy is established and helps avoid difficult decisions and situations.
Common examples of conditions caused by mutations in single genes (monogenic disorders) include spinal muscular atrophy (SMA), cystic fibrosis, and Fragile X disease. During the IVF process, PGD can be used to screen embryos for these conditions. Embryos that are not at increased risk for developing the single gene disorder are identified and preferentially transferred for the pregnancy. The goal of PGD testing is to help couples build healthy families.
To perform PGD testing, a set-up test is required. A unique probe is customized for each couple and used to perform PGD testing on embryos. To build the probe, blood samples from the couple and often from other family members are required. Igenomix’s team is made up of the world’s finest experts in the PGD field who are able to design probes for even the most rare and complicated mutations. Our set-up time needed to develop the probe is the fastest in the country.
Igenomix uses state of the art technology for PGD. Whenever possible, Igenomix uses a multiple detection approach to ensure the most reliable results. Using direct detection, PCR is used to detect the specific disease causing mutation. Linkage analysis uses PCR to detect informative STR markers that are linked to the disease-causing gene. Our multiple detection strategy minimizes the chances of no results or misdiagnosis due to allele drop out (ADO). With our technology, our PGD testing is 98-99% accurate.
2. Who should use PGD testing?
PGD is indicated for couples who have increased risk of having a child with a single gene disorder. Common examples of monogenic disorders are cystic fibrosis, fragile X syndrome, spinal muscular dystrophies (SMA), Duchenne muscular dystrophy (DMD), and Huntington disease. Some conditions are inherited in an autosomal dominant manner and can be inherited from an affected parent. Other conditions are inherited in an autosomal recessive manner and can be inherited from two unaffected carrier parents. Still other conditions are sex-linked and can be inherited from an affected father or a carrier mother. Not all genetic disorders are caused by mutations in single genes or can be tested for with PGD.
At Igenomix, we can perform PGD for virtually any single gene disorder. Below is a list of disorders commonly tested for at Igenomix.
Panel of Frequent Monogenic Disorders**
- Autosomal Dominant Polycystic Kidney Disease
- Autosomal Recessive Polycystic Kidney Disease
- Becker muscular dystrophy
- Beta thalassaemia
- Congenital adrenal hyperplasia (gene CYP21A2)
- Cystic fibrosis
- Charcot-Marie-Tooth type 1A
- Duchenne muscular dystrophy
- Familial amyloid polyneuropathy
- Fragile X syndrome
- Hemophilia A (F8)
- Hemophilia B (F9)
- Huntington disease
- Multiple endocrine neoplasia, type 2A
- Myotonic dystrophy (Steinert)
- RhD incompatibility
- Spinal muscular atrophy
- X-linked adrenoleukodystrophy
3. What are the advantages of PGD testing with Igenomix?
- Identify embryos affected with a genetic disorder prior to implantation
- Unique probe custom-designed for every couple
- Fastest PGD set-up in the country:
- 3 weeks for common disorders/mutations
- 6 weeks for rare disorders/mutations
- Complete PGD counseling at no additional cost with experienced genetic counselors
- Extremely flexible with every case. We understand each patient is unique
- World’s finest experts in the PGD field who are able to design probes for even the most rare and complicated mutations
- Senior team who analyzes results for every embryo along with double signature on all result reports
- Proprietary embryo biopsy buffer formulated to maximize DNA amplification yield
- 24/7 phone service with Laboratory Director or Manager
- On-site training of embryologists available
- Guaranteed outstanding customer service
1. To perform PGD for a single gene disorder, is it required to have identified the mutation causing the disease?
In most cases, documentation of the mutation responsible for the disorder is necessary. In some cases, a clinical report with a clear family history can be sufficient.
2. Should PGS for aneuploidy screening be performed in conjunction with PGD testing?
Aneuploidy is a numerical chromosome abnormality. Igenomix recommends that PGS for aneuploidy screening be performed in conjunction with PGD testing. Both tests can be done on the same embryo biopsy, so there is no additional risk to the embryo to do PGS testing. PGS for aneuploidy screens for abnormalities in chromosome numbers that could cause miscarriage or could result in the birth of a baby with birth defects and mental retardation. Down syndrome is an example of a genetic disorder that is caused by a numeric chromosome abnormality. The risk of having embryos with aneuploidy increases with maternal age. The goal of PGS testing is to identify embryos that are the most likely to develop to term and to be born healthy.
3. After the probe has been developed, how soon must IVF be completed?
After the probe has been developed, the IVF cycle and testing of embryos can be completed at the convenience of the patient and the clinic. The probe can be kept long term. Patients needing to delay IVF for longer than 6 months after the probe has been developed should make special arrangements with Igenomix.
4. If PGD testing has been done for a previous cycle, is there still a set-up time required for another PGD cycle?
No, there is no set-up time necessary for subsequent PGD cycles. This is because the same probe that was made for the couple can be used again for any future testing. If a probe has been made for previous PGD testing with Igenomix, we can proceed directly with embryo testing for future PGD cycles.