The BBC's Richard Hannaford on genetic testing

The report by the Nuffield Council on Bio-Ethics, an independent non-profit making organisation, says children should only be tested if it is in their best interests, for example, if there is treatment available which can help them in later life.

Otherwise, testing could lead to increased stigma and worry over a condition which may not actually develop.

The Nuffield Council says: "Many healthy people may carry gene variants with mental disorders, but usually not develop the condition, for example, late onset Alzheimer's Disease."

It continues: "The information gained about the likelihood or otherwise of a mental disorder would profoundly affect a person and those around them.

"If children are tested, it denies them the possibility of making their own choice in adulthood."

A spokeswoman for the Council added that testing could either encourage stigmatisation of children, a fatalistic attitude to illness or parent complacency, absolving parents of responsibility for a child's mental state.

She said a gene may lie dormant and could be triggered by social influences.

She believed the plethora of new discoveries about genetic influences might be swinging people too far away from the importance of social and environmental factors which influence mental health.

Complex causes

The Nuffield Council's report says genetic tests may be useful for devising new drug treatments, but they are unlikely to be able to diagnose mental disorders with more complex causes.

It states: "Even if a number of susceptibility genes were identified for a particular disorder, the report concludes that, without understanding their interaction, they would not be adequate for predicting individual risk."

The report, Mental disorders and genetics: the ethical context, says environmental and social causes can play a part and therefore the whole person must be considered, not just their genes.

Testing for genetic disorders could bring discrimination

Professor Martin Richards, who was on the working party which produced the report, said testing could open up a variety of choices, such as whether to have an abortion.

The report therefore recommends that people should have access to professional genetic counsellors.

It also calls for research into what the aims and outcomes of genetic counselling for mental disorders should be.

Discrimination

In addition, the Nuffield Council recommends that insurers and employers should not overemphasise the relevance of genetic information about mental disorders as this could lead to discrimination.

It wants the government and the insurance industry to monitor the use of genetic tests to prevent companies charging overly high premiums or refusing insurance.

It also calls for monitoring of the introduction of screening programmes for employees.

Other issues covered by the report include the need for genetic registers to be kept confidential and for research into mental disorders to be conducted with the patient's consent and at times when the patient is competent to make a decision.

Government advice

The report follows the recommendations of the government's Advisory Committee on Genetic Testing (ACGT).

It says foetuses should not be tested for genetic disorders and children should not have tests for inherited diseases which are incurable.

These include Huntingdon's Disease.

It stresses the need for people to be given full information and support concerning the implications of testing and for no tests to be carried out without a patient's consent.

The British Medical Association has welcomed the report, saying it highlights "the particular dilemmas" which arise from combining genetics with "the persistent fear and stigma attached to mental illness".