Who uses PGD?
The most common reason to use PGD is to avoid having a baby with a genetic disease. If a couple know that one of them has a genetic disease, or that they have a history of genetic disease in their family, they may not wish to pass the genes on to their child. They use PGD to select an embryo without the disease genes before going ahead with the pregnancy.
If a pregnant woman has tests that showed her fetus had a serious disease, then she and the baby’s father might have to decide whether to terminate the pregnancy. PGD avoids this unhappy situation.
Sometimes a family may already have a child who has a very serious disease, for example a type of cancer or rare genetic diseases such as Harlequin Ichthyosis, a life-threatening skin disorder.
If the family decide to have another baby which is genetically very similar to the ill child, then the new baby could help their older brother or sister. A classic example of such a disease is an extreme case of the blood disorder thalessaemia. This baby would provide a source of cells for the older child. Cells from the baby’s umbilical cord or bone marrow may be used to treat the sick brother or sister. Scientists use PGD to help decide which embryo is the best match for the sibling. You will often hear these children being referred to as ‘saviour siblings’.
Some people think it is unfair to create a child just to save an existing child. They worry that the sibling being created cannot have a say in the matter. There are also ethical concerns about hurting the saviour sibling. Taking blood from the umbilical cord after birth does not hurt the baby, but the removal of bone marrow, which is found deep inside the bone, can be painful.