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Medicine and Health

Mother at risk of chromosomal abnormalities gives birth to healthy baby girl

 A group of researchers from the Unitat de Biologia Cel·lular i Genètica Mèdica de la UAB formed by Dra M. Rius, MSc G. Daina, MSc L. Ramos, Dr J. del Rey, Dr A. Obradors, Dr J. Benet and leaded by Dra J. Navarro, and with the collaboration of a team from the Institut Universitari Dexeus formed by Dra M. Boada, MSc M. Parriego, DSc MJ Gómez, DSc L. Tuñon, MSc S Mateu, Dr B. Coroleu and Dr PN Barri, has achieved the birth of a healthy baby girl after applying Preimplantation Genetic Diagnosis (PGD) for risk of chromosomal abnormalities due to advanced maternal age. The chromosome analysis procedure used in this case, the rapid comparative genomic hybridisation (CGH) , which uses MetaSystems (IZASA) software,has been developed in the Unitat de Biologia Cel·lular i Genètica Mèdica de la UAB and has been published

References

Rius M, Obradors A, Daina G, Cuzzi J, Marquès L, Calderón G, Velilla E, Martínez-Passarell O, Oliver-Bonet M, Benet J, Navarro J. "Reliability of short comparative genomic hybridization in fibroblasts and blastomeres for a comprehensive aneuploidy screening: first clinical application." Hum Reprod. 2010 Jul

Preimplantation Genetic Diagnosis (PGD) for chromosome screening, allows to select only normal embryos for transfer to the uterus tries to prevent the birth of thouse with viable syndromes: Patau s (47, +13), Edwards (47, +18), Down (47, +21) or Turner (45, X0), or other abnormalities that will prevent embryo implantation.

In the techniques used in women of advanced maternal age, the European Society of Human Reproduction and Embryology has compiled an implantation rate of transferred embryos of about 14.9%. This low rate of implantation of embryos transferred has been attributed to the presence of abnormalities in chromosomes that are not usually analyzed.

Alternatively, this PGD studied all of the chromosomes of evolved embryos with rapid CGH allowing for simultaneous analysis of all chromosomes (chromosomes 1 to 22, and X and Y). It also has the advantage that the results achieved on four days, which allows selected embryos to be transferred to the uterus without freezing them.

In this family, the procedure to select the embryos was performed in collaboration with gynecologists and embryologists of Institut Universitari Dexeus, who performed the entire procedure of assisted reproduction.

Of the 13 zygotes obtained, 10 (83.3%) were evolving, producing embryos of 6-8 cells the third day. Cytogenetic analysis using rapid CGH diagnosis was obtained in all blastomeres analyzed.

Only one embryo (10%) was cytogenetically normal for all chromosomes, whereas eight of the embryos had alterations on the number of chromosomes. It should be noted that four chromosomes involved in these alterations, usually not analyzed were detected. Moreover three embryos would have been considered erroneously normal when applying usual techniques.

On five days, the embryo selected was transferred to the uterus. A genetically normal child, of whom the Prenatal Diagnosis had already confirmed the cytogenetic results obtained in the PGD, was born.

Rapid CGH in PGD is a useful tool to select embryos free of chromosomal abnormalities in all of the 24 different chromosomes and could increase the rate of implantation of embryos transferred in families at risk of alterations due to advanced mother Age.

Joaquima Navarro

Department of Cellular Biology, Physiology and Immunology

Joaquima.navarro@uab.cat