Genomics in general practice


Mental health conditions
☰ Table of contents


Practice point


There are currently no specific high-risk gene variants that are associated with mental health disorders that are useful for predictive testings in clinical practice.1,2

Some companies that offer personal genomic testing may include variants that are associated with increased risk of certain mental health conditions. The results are unlikely to have any clinical utility.

 


What do I need to know?


The causes of mental health conditions, such as schizophrenia, bipolar disorder and depression, are multifactorial, and include environmental, social and genetic factors.
Table 1 outlines the empirical risk according to family history for schizophrenia and bipolar disorder.
 

Table 1. Empirical risk of schizophrenia according to family history3,4

Risk (%)

Affected relative

Schizophrenia

Bipolar disorder

No close relative (general population risk)

1

2–3

Sibling

9

13

Parent

13

15

Sibling and one parent

15

20

Both parents

40

50

Second-degree relative

3

5

Monozygotic twin

40

70

Dizygotic twin

10

20

 


Genetic testing


While some genetic variants have been shown to be associated with mental health conditions, there is no genetic test that can predict mental illness with certainty.
Some commercial genetic tests available are used to tailor drug treatments to individuals with a mental health disorder (Pharmacogenomics: Summary). There are currently no Australian clinical guidelines to support such use.1,5

 


When should I refer?


There is no indication to refer patients with a family history of mental illness (eg couples considering pregnancy) to genetics services.

 


Resources for patients


Centre for Genetics Education, Fact sheet 59: Mental illness – Schizophrenia and bipolar disorder
National Library of Medicine (US), Bipolar disorder
National Library of Medicine (US), Schizophrenia


Genomics in general practice




 

 

  1. International Society of Psychiatric Genetics. Genetic testing and psychiatric disorders: A statement from the International Society of Psychiatric Genetics. Brentwood, TN: ISPG, 2017. Available at https://ispg.net/genetic-testing-statement [Accessed 20 December 2017].
  2. State MW, Geschwind DH. Leveraging genetics and genomics to define the causes of mental illness. Biol Psychiatry 2015;77(1):3–5.
  3. Harper PS. Practical genetic counselling. 7th edn. London: Hodder Arnold, 2010.
  4. Slater E, Cowie V. The genetics of mental disorders. London: Oxford University Press, 1971.
  5. Hamilton SP. The promise of psychiatric pharmacogenomics. Biol Psychiatry. 2015;77(1):29–35.

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