Preimplantation Genetic Diagnosis (PGD) by Array Comparative Genome Hybridization (CGH) and Blastocyst Biopsy

• Implantation rate [ Time Frame: three weeks after embryo replacement ] [ Designated as safety issue: No ]
  number of embryos implanted divided by number of embryos replaced. An embryo implanted is measured as a fetal sac by ultrasound observation.
  
  

• miscarriage rate [ Time Frame: up to the end of second trimester ] [ Designated as safety issue: No ]
  lost pregnancies, defined as pregnancies with an observed fetal sac that did not progressed to third trimester.
  
  
• Pregnancy rate per transfer [ Time Frame: three weeks after implantation ] [ Designated as safety issue: No ]
  pregnancy defined as the presence of a fetal sac. Pregancy rate per transfer defined as pregnancies divided by patients with a replacement of embryos.
  
  
• Pregnancy rate per retrieval [ Time Frame: three weeks after transfer ] [ Designated as safety issue: No ]
  pregnancy defined as the presence of a fetal sac. Pregancy rate per retrieval defined as pregnancies divided by patients with an egg retrieval.
  
  
• live birth rate [ Time Frame: 1 year after embryo transfer ] [ Designated as safety issue: No ]
  pregnancies that arrive to term divided by procedures with an egg retreival.
  
  

Rational for the study:

The goal of this study is to determine if the strategy employed for the Test group can solve two major problems in ART, one the still low implantation rate in women of advanced maternal age, and two the frequent occurrence of multiple pregnancies resulting from solving the first problem by replacing too many embryos.

Preimplantation Genetic Diagnosis (PGD) has been proposed as a potential means to achieve these goals, but so far, the results with day 3 biopsy and FISH analysis of 5-12 chromosomes has produced contradictory results, the difference between studies being explained by technical differences (Munne et al. 2010). Three technical developments have recently occurred that can change dramatically the efficacy of PGD. One, blastocyst laser assisted biopsy, which seems less detrimental than cleavage stage biopsy; Two, vitrification of embryos which allows those blastocysts to be frozen with little or no loss of viability, and three, chromosome comprehensive screening techniques, such as array CGH (Gutierrez-Mateo et al. 2011) which allow for the detection of all chromosome abnormalities.

Preliminary data from our center indicates that the technique to be used, an improvement on our prior technique CGH, will result in a very significant improvement in implantation rates and a reduction in miscarriage rates, thus justifying the use of single embryo transfer in this set up.

Supportive Preliminary Research:

In a recent study, the investigators observed a 1.6 fold increase (p < 0.001) in implantation rate when aCGH was applied to blastocyst embryos (Schoolcraft et al. 2010). The test group used CGH, an older and less sensitive iteration of the technique to be used in the proposed study - array CGH. Array CGH has a 6 megabase resolution and screens for 30% of all DNA bases (compared to 0.1% of SNP arrays). With array CGH the false positive and false negative rate is 0% when biopsying blastocysts, and 3% when biopsying day 3 embryos (Gutierrez Mateo et al, 2011). Based on our preliminary data, patients with 5 or more day 3 embryos and less than 43 years of age are the most likely to benefit from PGD, since they produce enough embryos and enough normal embryos so a selection technique, like PGD could chose them and improve their reproductive odds.

Also our PGD preliminary data shows a < 10% of embryo demise after implantation for a population 38 of age (expected would be about 28%).

Study Hypothesis The investigators foresee a significant increase in implantation rates in the Test group compared to the Control group. The investigators calculated that 60 patients in each arm would be needed to achieve a significant increase in implantation rates (p < 0.05) with a power of 80%, based on a comparative study in which the investigators observed a 1.6 fold increase in implantation rate (Schoolcraft et al. 2010).

Study population, interventions:

see below.