Journal de Fertilization: In Vitro - IVF-Worldwide, Médecine de la Reproduction, Génétique & Biologie des Cellules Souches
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Assessment of 19,803 Paired Chromosomes and Clinical Outcome from First 150 Cycles using Array CGH of the First Polar Body for Embryo Selection and Transfer

Fishel S, Craig A, Lynch C, Dowell K, Ndukwe G, Jenner L, Cater E, Brown A, Gordon A, Thornton S, Campbell A, Berrisford K, Kellam L and Sedler M

Background: Meiosis 1 errors are believed to be the largest single cause of clinical embryo failure and early miscarriage. Following the failure of FISH technology and concerns over embryo mosaicism, our aim was to assess paired chromosome status and error rates, and predict oocyte aneuploidy using the metaphase2 polar body with a novel Array CGH platform as a means to select embryos for couples with multiple IVF failures.

Methods: The PB1 was removed from metaphase 2 oocytes using a laser-assisted breech of the zona pellucida to effect the biopsy. Reliable 23-paired chromosome analysis was obtained, and in time for fresh embryo transfer. It was a non- randomised investigation in patients seeking this technology as a result of previous multiples failures of IVF.

Results: 134 couples presented for 150 cycles of array CGH with a median age of 41.0. 861 polar bodies were evaluated, 67.4% and 32.6% were aneuploid and euploid, respectively. 19,803 paired chromosomes were analysed, 3.5% and 3.4% of chromosome errors resulted in either a gain or loss, respectively. There was a positive correlation between female age and aneuploidy, but no correlation with numbers oocytes harvested. 26% of cycles (n=39) failed to achieve embryo transfer (ET) as none of the oocytes were euploid. The live birth rate per ET and implantation was 24.1% and 27.7%, respectively, and 5.2% of chemical pregnancies (1.9% of transfers) resulted in a dizygotic multiple pregnancy.

Conclusion: Array CGH was proven to generate robust chromosome information. Chromosome segregation error rates were found to be inversely proportional to chromosome length and proportional to the G/C base content. Clinically, the transfer of a single embryo after PB 1 array CGH analysis appeared to generate improved implantation rates in women with very poor prognosis, whilst reducing the risk of a multiple pregnancy.