Companies that offer genetic tests for certain diseases are to face restrictions to stop them from providing inaccurate information.
Genetic testing companies calculate the risk of disease by taking saliva or blood samples, but experts have warned the results may not be correct.
The Human Genetics Commission (HGC), which advises the UK government on genetics, has drawn up new guidelines to ensure that companies adhere to the basic principles of truthful marketing, principles of consent, data protection and scientific rigour.
The body said that companies should offer counselling before and after a test.
Customers should also be informed of all possible outcomes, and tests used need to be backed up by scientific evidence.
HGC commissioner Dr Frances Finter said some tests can cause considerable surprise or concern to those taking them. Others could give false reassurance and some are of doubtful value.
“We need a set of off-the-shelf principles that can be used everywhere.” Finter said.