Array-CGH in polar body analysis

Abstract

OBJECTIVE: Chromosomal aneuploidies are the major cause of pregnancy loss or implantation failure. Therefore many efforts are in progress to establish assays for the detection of aneuploidies in preimplantation genetic diagnosis (PGD). In the past years, we were able to gain much experience with polar body (pb) analysis by fluorescence in situ hybridisation (FISH). Both aneuploidy testing and translocation analysis are well established in our lab. The main disadvantage of this technique is that only a maximum of 10 chromosomes can be analysed. DESIGN: In order to analyse all 23 chromosomes, we are using an Array-CGH procedure. To get sufficient DNA from the sample, each pb is amplified by whole genome amplification. The array carries 600 bac clones covering the whole genome to detect gain or loss of chromosomes. MATERIALS AND METHODS: To test the feasibility in a clinical setting with the restriction of the German embryo protection law, we started a clinical trial, including 10 patients (mean age 37,3 years). Following a standard IVF protocol (2.-4. cycle) oocytes retrieval was carried out in 5 patients so far (mean no of MII oocytes 13). Both pbs of 5 oocytes from each patient were extracted and amplified. RESULTS: All array analyses were successfully carried out, leading to an average of 36% (1,8 out of 5) euploid oocytes. Following the embryo transfer of a maximum of 2 day-3-embryos, 2 clinical pregnancies could be achieved in our 5 patients. CONCLUSIONS: The study is ongoing and so is the follow up of the patients. Due to our preliminary results, we conclude that further studies, especially to confirm the benefit in regard to clinical pregnancy and baby take home rates for particular subgroups of patients, need to be carried out.