New guidelines issued by the UK General Medical Council (GMC) will allow doctors to disclose genetic information to relatives - even when patients object, if there are compelling medical reasons for doing so.

The guidance, which comes into effect on 12^th October, acknowledges that confidentiality is not always absolute; disclosing information about a genetic link to a disease may protect another individual from serious harm. For example, if a patient is diagnosed with a hereditary form of cancer, a doctor will now be able to inform relatives about the potential risk the genetic link could carry. Awareness of such a genetic risk could prompt investigation for the genetic mutation responsible and regular screening, thereby improving the chance of early detection and long-term prognosis.

Foremost, doctors will explain to a patient diagnosed with a hereditary form of a disease that family members may also carry the genetic trait. Doctors are also advised to discuss what details a patient wishes to share, with whom, and under what circumstances, so that in cases of diminished capacity to communicate this information, a doctor may assume this role. When a patient cannot be persuaded to tell relatives who are at risk, doctors should weigh up the risks and benefits for both patient and relatives and make a decision whether to inform them. The guidelines recognise that this scenario is more likely to occur where family relationships have broken down or children have been adopted, in which case the doctor may take the necessary measures to ensure they are made aware of their risk. Where possible, the identity of the original patient should be protected however.

Dr Henrietta Campbell, who chaired the GMC's working group on confidentiality, explains: 'Confidentiality is central to trust between patients and doctors, but it is still an area of ethics which continues to challenge doctors more than any other. 'This guidance makes clear that, in the first instance, doctors should explain to a patient if their family might be at risk of inheriting a condition. In those circumstances, most will readily share information about their health. However, if a person refuses, it is the responsibility of the doctor to protect those who may be at risk', she said.