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Mental Health

Presentation: Adult with schizophrenia

At least 2.5% of patients with schizophrenia carry an identifiable neurodevelopmental copy number variant. This is likely to be more prevalent in patients with intellectual disability, neurodevelopmental conditions, congenital anomalies and/or a positive family history.

Example clinical scenario

A 25-year-old patient is diagnosed with schizophrenia. They also have a mild learning disability and were diagnosed with autism spectrum disorder (ASD) at primary school age. They were born with a ventricular septal defect and experienced frequent seizures in childhood. There is a family history of ASD, attention-deficit hyperactivity disorder (ADHD) and psychosis. You are considering whether the patient’s psychosis could be a symptom of a broader genetic condition and wish to explore what genomic testing is available and appropriate.

When to consider genomic testing

The Royal College of Psychiatrists recommends testing for rare copy number variants (CNVs) in people with schizophrenia and co-occurring conditions, as the diagnostic yield is likely to be higher in this group. These conditions include neurodevelopmental disorders, marked cognitive impairment, congenital anomalies, dysmorphology and unusual medical presentations.

Early-onset schizophrenia is also associated with genomic diagnoses and the College recommends testing children and young people with schizophrenia, especially if other clinical features are present.

Schizophrenia is not currently listed as a condition eligible for genomic testing in England, Scotland or Northern Ireland.

In Wales, the All Wales Psychiatric Genomic Service (AWPGS) accepts referrals for patients with a psychotic disorder, plus one or more of the following:

  • treatment resistance;
  • personal history of neurodevelopmental disorder;
  • personal history of congenital anomaly;
  • family history of psychotic disorder/treatment resistance;
  • family history of neurodevelopmental disorder; and/or
  • family history of congenital anomaly.

What do you need to do?

  • Patients in Wales can be referred to the AWPGS. Please consult the AWPGS website for up-to-date information on referral criteria and testing offered.
  • Schizophrenia is not currently listed as a condition eligible for genomic testing in England. Consult the National Genomic Test Directory for recent updates to testing policies.
  • If you suspect that psychosis is a presenting symptom of a defined genetic condition or syndrome, consider specific testing via the test directory:
    • Microarray should be requested for patients in whom there is a clinical suspicion of 22q11.2 microdeletion. See ‘Presentation: Clinical suspicion of 22q11.2 deletion syndrome‘ for more information.
    • R58 Adult onset neurodegenerative disorders. This panel investigates single gene causes of adult-onset neurodegenerative conditions. The test can ordered as R58.4 (whole genome sequencing (WGS)) or R58.5 (non-WGS). R58.4 is the main test to consider, however R58.5 may be required to detect more complex short tandem repeats (STRs). Consider checking with the laboratory whether a separate R58.5 test is required in these cases.
    • R68 Huntington disease. This should be used if Huntington disease is the primary suspected diagnosis.
    • R172 Wilson disease. This should be used if clinical investigations suggest a possible diagnosis of Wilson disease.
  • For patients in whom there is a history of epilepsy, a different diagnostic pathway may be required. See ‘Presentation: Adult with epilepsy likely to be genetic in origin‘ for more information.
  • For patients with intellectual disability, you may wish to consider the following tests:
    • R377 Intellectual disability – microarray only. This will investigate chromosomal causes of unexplained moderate/severe/profound intellectual disability.
    • R29 Intellectual disability. This will investigate single gene causes of global developmental delay or intellectual disability via a WGS panel. This is for individuals with moderate/severe/profound intellectual disability where clinical features are suggestive of an underlying monogenic condition.
      • Note: this test is not available to order by psychiatry; requesting specialties currently include clinical genetics, metabolic medicine, neurology and paediatrics (including community paediatrics).
    • R27 Paediatric disorders. This should be used for children and adults with features suggestive of a syndromic diagnosis.
      • Note: this test is not available to order by psychiatry; requesting specialties currently include clinical genetics, metabolic medicine and paediatrics (including paediatric neurology and community paediatrics).
  • For more information about genomic conditions associated with psychosis, see our dedicated Knowledge Hub resource.
  • For tests that do not include WGS, including R58.5, R68, R172 and R377:
  • For WGS-based tests, including R27, R29 and R58.4, this will need:
  • These tests are DNA-based, so an EDTA sample (purple-topped tube) is required.
  • Information about patient eligibility and test indications was correct at the time of writing. When requesting a test, please refer to the National Genomic Test Directory to confirm the right test for your patient.

Resources

For clinicians

References:

For patients

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  • Last reviewed: 06/03/2025
  • Next review due: 06/03/2026
  • Authors: Dr Jo Doherty, Donna Duffin
  • Reviewers: Dr Rachel Irving, Dr Kim Kendall