Mentally ill patients need protection from inappropriate genetic testing

BMJ 1998; 317 doi: (Published 03 October 1998) Cite this as: BMJ 1998;317:903
  1. Alex Brooks
  1. BMJ

    People with mental disorders must be protected from inappropriate genetic testing, a report from the Nuffield Council on Bioethics has recommended.

    The working party, chaired by Dame Fiona Caldicott, principal of Somerville College, Oxford, investigated the ethical issues surrounding research and its applications into the genetics of mental disorders. Dame Fiona said: “In response to the recent and frequent discovery of genes associated with a variety of diseases, there is a temptation to rely on ‘geneticisation' as the ultimate answer to diagnosis and prevention.”

    Most mental illness is multifactorial, with genes having a variable role. The genetic contribution is only about 5% in bulimia nervosa but rises to 50-70% in schizophrenia. The working party concluded that genetic tests will not be particularly useful in the near future for diagnosing mental illness, with the exception of rare mendelian disorders, such as early onset Alzheimer's disease.

    Identifying so called susceptibility genes (alleles) will probably be more useful for drug design than diagnosis. The authors consider that the understanding of susceptibility genes, such as the ApoE4 gene, and environmental influences affecting mental illness is not yet sufficiently advanced for predicting individual clinical risk.

    Unless there is a “clear medical benefit,” genetic testing, especially in children, should be strongly discouraged. Cases of such benefit include the Guthrie test for newborn infants to detect children with phenylketonuria, for which successful treatment is available. In cases of adoption testing needs to be considered carefully with appropriate guidance, recommends the report.

    In cases where definitive testing is currently available most members of the affected family choose not to be tested. Only 5-10% of young adults at risk of Huntingdon's disease--a dominant disorder that is invariably fatal in middle age--currently choose to be tested.

    Genetic testing has implications for a whole family. The report recommends that confidentiality should be preserved if possible but that information may be disclosed to close family members in exceptional circumstances. The authors emphasise that clinicians must realise that this information will probably then reach the rest of the family, even against the wishes of the original family member.

    The committee considers that the moratorium (to be reviewed next year) preventing the disclosure of results of existing genetic tests to insurance companies should be lifted only when research shows the actuarial relevance of specific tests.

    Mental Disorders and Genetics: the Ethical Context, from the Nuffield Council on Bioethics, 28 Bedford Square, London WC1B 3E, price £20.

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