Oligonucleotide Arrays <i>vs.</i> Metaphase-Comparative Genomic Hybridisation and BAC Arrays for Single-Cell Analysis: First Applications to Preimplantation Genetic Diagnosis for Robertsonian Translocation Carriers

<div><p>Comprehensive chromosome analysis techniques such as metaphase-Comparative Genomic Hybridisation (CGH) and array-CGH are available for single-cell analysis. However, while metaphase-CGH and BAC array-CGH have been widely used for Preimplantation Genetic Diagnosis, oligonucleotide array-CGH has not been used in an extensive way. A comparison between oligonucleotide array-CGH and metaphase-CGH has been performed analysing 15 single fibroblasts from aneuploid cell-lines and 18 single blastomeres from human cleavage-stage embryos. Afterwards, oligonucleotide array-CGH and BAC array-CGH were also compared analysing 16 single blastomeres from human cleavage-stage embryos. All three comprehensive analysis techniques provided broadly similar cytogenetic profiles; however, non-identical profiles appeared when extensive aneuploidies were present in a cell. Both array techniques provided an optimised analysis procedure and a higher resolution than metaphase-CGH. Moreover, oligonucleotide array-CGH was able to define extra segmental imbalances in 14.7% of the blastomeres and it better determined the specific unbalanced chromosome regions due to a higher resolution of the technique (≈20 kb). Applicability of oligonucleotide array-CGH for Preimplantation Genetic Diagnosis has been demonstrated in two cases of Robertsonian translocation carriers 45,XY,der(13;14)(q10;q10). Transfer of euploid embryos was performed in both cases and pregnancy was achieved by one of the couples. This is the first time that an oligonucleotide array-CGH approach has been successfully applied to Preimplantation Genetic Diagnosis for balanced chromosome rearrangement carriers.</p></div

Examples of a) totally coincident profiles and b) highly similar profiles, obtained with oligonucleotide aCGH and BAC aCGH.

<p>Oligonucleotide aCGH profiles are shown at the top of the figure and BAC-aCGH profiles are shown below.</p

Examples of a) oligonucleotide aCGH profiles and b) their corresponding mCGH profiles.

<p>The first profile from a) and b) correspond to one blastomere with totally coincident profiles between techniques, and the second profile from a) and b) correspond to one blastomere with highly similar cytogenetic results.</p

Cytogenetic results obtained from human single blastomeres analyzed by BAC aCGH and oligonucleotide aCGH.

<p>BL: Blastomere; SC: Sexual chromosomes, A: Aneuploidies; S: Segmental imbalances.</p><p>Cells 19-34: PGDs for six different couples with either male factor or repeated implantation failures.</p><p>Cytogenetic results obtained from human single blastomeres analyzed by BAC aCGH and oligonucleotide aCGH.</p

Cytogenetic results obtained from human single blastomeres analyzed by mCGH and oligonucleotide aCGH.

<p>BL: Blastomere; SC: Sexual chromosomes, A: Aneuploidies; S: Segmental imbalances.</p><p>Cells 10-13: Globozoospermia PGD case, cells 14-18: Robertsonian translocation carrier PGD case (45,XY,der(13;14)(q10;q10)).</p><p>Cytogenetic results obtained from human single blastomeres analyzed by mCGH and oligonucleotide aCGH.</p

Resolution, procedure duration and costs of mCGH, BAC aCGH and oligonucleotide aCGH (8x60K and 4x180K formats).

<p>One person performing analysis.</p><p>Resolution, procedure duration and costs of mCGH, BAC aCGH and oligonucleotide aCGH (8x60K and 4x180K formats).</p