Rabu, 04 April 2012

Boy or girl? Technology allows you to choose the sex of your baby


Throughout history, humans have wished for a child of one sex or the other. At last gender selection is scientifically feasible. The most intriguing method is an in vitro fertilization technique called preimplantation genetic diagnosis.

 

Gender selection techniques

Preimplantation genetic diagnosis (PGD) was originally designed for detecting genetic diseases. It allows genetic analysis to be performed on early embryos prior to implantation and pregnancy. It was intended to exclude genetically defective embryos before they have a chance to develop. Typically one or both partners have been genetically screened and found to be a carrier for a inheritable genetic disorder.
The technique of preimplantation genetic diagnosis involves the removal of eggs from the woman and fertilization within the lab using standard IVF (invitro fertilization) techniques to create embryos. Embryos are then biopsied under microscopic observation and control to obtain one or two sample cells (blastomeres) for genetic analysis using either specialized DNA amplification or fluorescent hybridization systems. Male and female embryos can be differentiated by examining their chromosomes. If they spot a Y, they know it's male. After determining the sex of embryos, doctors implant the desired ones. While more invasive and costly (around 20,000 US Dollars) than other methods of gender selection, the success of preimplantation genetic diagnosis is virtually guaranteed.
An FDA trial involving a sophisticated sperm-sorting technology called MicroSort is more than halfway to completion. Through an extensive marketing campaign Genetics and IVF Institute (GIVF) were able to recruit more and more cases each month.
This experimental technique separates girl-producing sperm, which carry X chromosomes, from boy-producing sperm, which have Y chromosomes using an electrode that gives X's a positive charge and Y's a negative one. Charged plates then attract and separate X's and Y's, channeling them into different receptacles. Either sample can now be used to fertilize a woman's eggs, depending on the gender requested.
A third low-cost method which has been around fro decades is the Ericsson technique.  Sperm are poured on a viscous layer of fluid. The sperm carrying Y chromosomes swim faster than sperm carrying X chromosomes, reaching the bottom of the test tube sooner. They can then be extracted and used for insemination. Supporters of this technique claim an 85 percent chance of producing a boy. Critics say the odds are no better than 50% (rendering it ineffective).

Ethical issues

If couples can request a baby boy or girl, could picking one gender over the other become the 21st century's form of sex discrimination? Or could this upset the ratio of males to females? These explosive issues are undergoing heated debated in the medical circles. Preimplantation genetic diagnosis also takes us back to the question of whether the destruction of an embryo is equivalent to the murder of a human. Children are going to hold their parents responsible for having made them this way. Currently there are no laws against performing gender selection in the United States.

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