How are Designer Babies made?

Today it is possible to choose the sex of the embryo using advanced reproductive techniques during IVF. Doctors can do this using one of two methods. The first method is to sort out a sample of the father's sperm and only fertilize the egg with either 'male' sperm or 'female' sperm. The second method is Pre-implantation Genetic Diagnosis (PGD), which is used to screen-out embryos likely to have a genetic disease.

PGD takes place during IVF where the sperm fertilizes the egg in a "test-tube" in a laboratory. The fertilized egg grows for a few days before a single cell is removed and tested to find out either the sex of the embryo or if abnormal genes are present. Surprisingly, removing one cell does not seem to affect the embryo's development.

Determining the sex of an embryo can be useful because some genetic diseases, like hemophilia and Duchenne Muscular Dystrophy, only show themselves in male babies. If the parents have a history of male-related disease, then techniques such as PGD, can be used. Doctors then choose a healthy female embryo without the faulty gene and implant this into the mother's womb to grow into a healthy baby.

In most countries sex selection is only permitted to avoid diseases that are linked to a certain sex. In Britain it is illegal to select the sex of a child just because the parents want either a boy or a girl.

To date germ line therapy has been carried out on animal eggs, sperm and embryos but at present it is illegal to do this on humans.
It is however possible to modify the faulty genes in the cells of a grown child or an adult to cure diseases like cystic fibrosis. This is called body cell gene therapy. Gene therapists have recently succeeded in curing a toddler of a life-threatening genetic condition that prevented him from developing an immune system. The toddler had a condition called severe combined immunodeficiency (SCID), which is caused by a single faulty gene.

Up until the body cell gene therapy treatment in March 2001, the 18-month-old boy lived in a sterile 'bubble' to prevent him picking up infections. Doctors took some of his bone marrow and used a non-infectious virus to carry a healthy version of the gene into the immune cells of his bone marrow.

The 'new improved' bone marrow was then re-implanted into the toddler where it gradually produced new immune cells. These immune cells entered the toddler's blood stream and protected him from infection. Now, thanks to gene therapy he is free to run around and his immune system is similar to that of other children his age.