A company in the US is offering potential parents the chance to test whether their future offspring might develop serious health problems by selling them home genetic test kits. The company Counsyl allows customers to send a saliva sample via the post, which is used in conjunction with DNA chip technology to screen if the person is a carrier for a single genetic mutation known to cause a disease. If both parents carry the same mutation, there is a one in four chance that any child they conceive will develop the disease.

The test checks for diseases such as cystic fibrosis, Tay-Sachs or sickle cell anaemia. If the couple is found to be at risk of passing such traits onto their children, steps can be taken to prevent this, such as using genetic screening of embryos to which are implanted for IVF. The company stated that 35-40 per cent of couples tested were carriers for at least one condition, and in 0.6-0.8 per cent of the cases, both parents in the couple were found to be carriers for the same genetic mutation.

Genetic tests are already carried out by hospitals, but only for a few of the more common conditions, and they often cost a lot of money. Counsyl offers its test for over 100 diseases, and charges $698, much less than the old blood tests cost, according to The New York Times (NYT) newspaper.

Balaji Srinivasan, the company's chief technology officer, told the NYT: 'The goal is not to maximise revenue but to bring the benefits to humanity. Nothing is more relevant than making sure your child doesn't die from a preventable disease'.

Feelings about Counsyl are mixed, according to quotes obtained by the NYT. Elena Ashkinadze, a prenatal genetic counsellor at the Robert Wood Johnson Medical School in New Jersey, said: 'As a genetic counsellor, I've been waiting for this for a really long time'. But Michael S Watson, executive director of the American College of Medical Genetics, said that many mutations are silent, meaning there is no risk to offspring. Couples might be needlessly worried.

Other experts told the NYT that a rise in identification of carriers would overwhelm the use of genetic counsellors. Also, the test looks for only 100 diseases - there are thousands of genetic conditions identified so far, which will not be tested for.