The impact of discoveries in medical genetics

There are some 4000 known, simply-inherited genetic disorders and, in aggregate, they are the cause of much suffering in 1–2% of the population. The common disorders include cystic fibrosis, sickle cell disease, the thalassaemias, fragile-X syndrome, Duchenne muscular dystrophy, haemophilia A, Huntington's disease, neurofibromatosis and adult polycystic kidney disease.

We ‘fight’ germs, but such language seems inappropriate for genetic disease because our genes, whether faulty or not, are an integral part of our makeup. Genetic testing can forewarn potential parents, but also pose moral dilemmas. Genetic knowledge can impose a burden of choice: a choice of whether to forgo children, trust to luck or seek prenatal diagnosis with the option of abortion if the baby is affected.

Although it is widely recognised that improvements in the treatment of genetic disease are desperately needed, some fear that ‘tinkering’ with our genes and the use of modified viruses as vehicles, or vectors, to deliver new genes to the body might be dangerous in some way to the population at large. Informed public debate needs an informed public, and that includes health professionals. Families facing these issues need help: genetic services, counselling and support in coming to a decision that is right for them.

What follows is intended as a simple guide to how genes work and sometimes fail. It explains how genetic tests are done and touches on some of the issues raised by advances in genetic testing.