Our Services: PGD

Recent advancements in embryo micromanipulations and molecular genetics made it possible to detect practically any human genetic disorder by analyzing a single cell. So far, the most exciting application of this fact is Preimplantation Genetic Diagnosis (PGD). Offered by a few centers in the US and Europe, PGD provides for IVF patients a unique opportunity to safeguard their pregnancy and future children against the most common genetic disorders. Since only normal embryos are being transferred to establish a pregnancy, genetic abnormalities are not transmitted into the next generation. At present, the majority of PGD cases are performed using the technique of fluorescent in-situ hybridization (FISH) on a single blastomere nucleus.

The most common indications for PGD are:

• Advanced Maternal Age (AMA): recommended for IVF patients over 36 years of age
• Recurrent Pregnancy Loss (RPL)
• Failed previous IVF cycles
• Family Balancing, a.k.a. “Sex Selection”
• Sex-linked genetic disorders
• One of the parents is a carrier of chromosomal translocation
• One of the parents is a carrier of chromosomal inversion
• One or both parents are carriers of a single-gene disorder

PGD-FISH is a four-step procedure:

1. Biopsy of a single cell (blastomere) from a 3-day old human embryo
2. Blastomere fixation
3. Hybridization of a fixed blastomere nucleus with fluorescein-labeled probes
4. Computer-assisted FISH analysis

The first two steps are usually performed on-site, using the facilities of the IVF lab. Any IVF center which is able to perform ICSI procedure has practically all the equipment necessary for embryo biopsy. If any equipment is missing or inadequate for a safe embryo biopsy/ blastomere fixation, we bring our own equipment to the host IVF lab.

Slides with fixed blastomeres are transported to our facility for FISH analysis. For PGD testing for aneuploidy or sex selection, the results are obtained and faxed to the host lab by the end of the day 3. Consequently, embryo transfer may be performed on Day 4 of embryo development. Compared to the standard practice of Day 3 embryo biopsy and Day 5 blastocyst transfer, this provides superior pregnancy rates for the patients of AMA or the patients with low number of embryos available for PGD testing.

At ViaGene Fertility, we have a few “standard” chromosome panels for the testing of Two (X+Y), Three (21+X+Y), Five (13,18,21,X,Y or 13,16,18,21,22), or Nine (13,15,16,17,18,21,22,X,Y) chromosomes. Call us, or read through our “select your baby” section for our recommendations regarding the best panel for your specific case. PGD for any other chromosome and practically any kind of chromosomal aberrations can be requested, granted that you give us at least a two-week notice.

PGD-PCR is performed as follows:

• Biopsy of a single cell (blastomere) from a 3-day old human embryo
• Blastomere transfer into PCR tube with a lysis buffer
• Transportation in a deep-frozen state to the genetic lab for analysis
• Results are usually obtained by noon on Day 5 of embryo development

PGD-PCR was first introduced in 1990 by Dr. Handyside group in England and Dr. Verlinsky team in the US (see “Our Publications”). Limitations of this technique had been largely overcome over the years, but PGD-FISH is nevertheless preferable for sex-linked disorders.

One picture is worth a thousand words… Please, take a look at the embryos of one of our IVF patients. Without PGD, an embryo with trisomy 21 (Down’s Syndrome), being morphologically second best, would have been selected for transfer!