Increasingly sophisticated genetic tests make it possible for parents to choose their baby’s traits.
By Amber Angelle
For just an extra few thousand rand, women undergoing in vitro fertilisation (IVF) could one day choose to have a baby boy with perfect vision, an aptitude for sports and a virtual lock on avoiding colon cancer. Fertility clinics in the US currently offer not only to screen for diseases, but also to choose gender. They are not yet offering any further customisation, but that could change as genetic mapping gets faster and easier.
Last year, a California company said it could screen for hair and skin colour, but soon retracted the claim amid a fi restorm of protest. (Research like this has prompted Pope Benedict to condemn “the obsessive search for the perfect child”.) The best screening test on the market is called pre-implantation genetic diagnosis. PGD, developed to prevent births of children with severe disorders, screens chromosomes from one or two of an embryo’s cells for abnormalities. Depending on the results, the IVF embryo is either implanted in the mother, donated for research or destroyed.
Now, researchers at the privately run Genetics & IVF Institute in Virginia have developed a test called karyomapping. The new procedure compares the genetic maps of parents and embryos to detect 15 000 known genetic disorders. It could also be used to choose traits such as intelligence or skin colour. “The future of genetic screening will really depend on what people want,” says Elizabeth Ginsburg, former president of the Society for Assisted Reproductive Technology. “If that means creating so-called designer babies, we’re going to need a lot more regulation.”
Three ways babies are born to specifications.
¨ Parents with children who suffer from leukaemia or anaemia and who could benefit from stem cell treatment can order up a sibling with the right genetic material. DNA from an embryo is analysed to find a human leukocyte antigen gene match between an embryo and the child. Nine months later, when the baby is born, the stem cells are retrieved from umbilical cord blood.
Pink or blue
¨ A 2006 survey conducted by the Genetics and Public Policy Centre found almost half of US fertility clinics offered non-disease-related sex selection through PGD embryo screening. A new technique in clinical trials may offer a less expensive method. Originally developed by the US Department of Agriculture for use in cattle, the new method analyses sperm instead of embryos and uses colour and fluorescence to sort male chromosomes from larger female ones.
¨ Parents with a family history of diseases such as cystic fibrosis, sickle cell anaemia and muscular dystrophy have a significant chance of passing the gene mutation that causes the disease on to their children. PGD can screen embryos for those conditions. It can also screen for genes that don't guarantee illness, but which are associated with higher risks of breast and colon cancer, and Alzheimer's disease.