Embryo screening could help parents avoid passing on inheritable diseases
Developed by a team of Spanish geneticists, a new genetic screening method makes it possible to control all stages of child development, starting with the embryo before it is implanted in the womb to improve the chances of having a healthy baby.
Most educated women today tend to pay greater attention to their education and career than their counterparts in previous generations. They may spend more years in university and also much time climbing up the corporate ladder after graduation. Many marry late in life and have children at an older age.
As women get older, it is known that their eggs become less and less fertile. However, genetics can sometimes play a part in infertility. Genetic abnormalities can affect an embryo’s ability to grow. This can, as a result, cause recurrent miscarriages.
Science can help women who face reproductive challenges with infertility treatments such as in vitro fertilisation. With more advanced technology, science can also help women ensure that a newborn baby is healthy and free of genetic diseases. This procedure is widely known as pre-implantation genetic screening (PGS).
In PGS, doctors examine the aneuploidies – abnormal numbers of chromosomes – which are closely associated with miscarriage. In particular, comparative genomic hybridisation (CGH) is a well-established procedure allowing the study of all chromosomes simultaneously.
CGH is generally prescribed for women who have undergone unsuccessful in vitro fertilisation, as it allows the observation of the development of an embryo from the eight-cell stage. If the doctor is sure that the embryo is not at risk for serious diseases, it can be safely implanted into the womb.
Now, in her doctoral thesis, Mariona Rius from the Cell Biology and Medical Genetics Unit of the Universitat Aut?noma de Barcelona in Spain developed the so-called short CGH which allows the full chromosomal study of embryonic cells in significantly reduced time. The value of the new method lies in that the embryo analysed does not need to be cryopreserved.
In a genetically healthy embryo, there should be 2 chromosomes for each of the 22 chromosome kinds, as well as a bouquet of XX female or XY male chromosomes. More than two chromosomes can lead to defective embryos. This problem can lead to an embryo that may not be able to develop and implant, or will miscarry
Equipped with this crucial genetic information, doctors can ensure with quite reasonable certainty that the embryos returned to the womb are those offering women a god chance of a healthy pregnancy. The implantation rate using the short CGH method can reach up to 60%.
To date, it has been successfully used in a couple where the man was a carrier of two chromosomal translocations. Specifically, in three consecutive cycles of in vitro fertilisation, an embryo without chromosomal ‘abnormalities’ was implanted into the woman who is currently in the third trimester of her pregnancy.
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Data Source Provider: Universitat Aut?noma de Barcelona; Fertility and Sterility
Document Reference: Rius, M., et al. (2011) Reliability of short comparative genomic hybridization for the detection of unbalanced chromosome segregations in PGD of translocations, Fertility and Sterility, in press.
Subject Index: Biotechnology; Coordination, Cooperation; Research ethics; Medical biotechnology; Medicine, Health; Scientific Research