Deciding whether to perform a genetic test for a person with developmental disability

There are a number of benefits from determining a specific aetiology for developmental disability, although each family will have their own reasons for seeking a diagnosis. The person with developmental disability should be involved in decision making around genetic testing whenever possible. Fact sheets on genetic testing are available from New South Wales Health Centre for Genetics Education. For advice on consent, capacity and decision making in people with developmental disability, see here.

Before consideration of genetic testing, a thorough history and examination remain important parts of a diagnostic evaluation. See advice in Assessing developmental delay and disability. Specialist advice is recommended. Information is also available in the Royal Australian College of General Practitioners (RACGP) Genomics in general practice guidelines. Practitioners may need to liaise with others involved in the person’s care to ascertain whether testing has been done previously.

If genetic testing is performed, test results should be clearly recorded in the person’s medical history.

A specific diagnosis of a developmental disability can provide the person, their family and their treating clinicians with information about the expected clinical course, and avoid the need for other expensive and invasive tests. A diagnosis can inform early interventions, which improve health and functional outcomes in people with developmental disability of all ages.

Note: A specific diagnosis can provide information about the expected clinical course, and avoid the need for other expensive and invasive tests.

For many disorders, condition-specific management and surveillance guidelines are available; see Syndromes and disorders associated with developmental disability for links to information on a range of developmental disability syndromes and disorders. A diagnosis made in childhood provides information about chance of recurrence in future pregnancies for the parents and, where relevant, the options of prenatal diagnosis and pre-implantation genetic testing.

The provision of condition-specific support is valued by people with developmental disability and their families; even those affected by rare disorders are often able to connect online across the world with similarly affected people and their families. Syndromes and disorders associated with developmental disability includes links to support organisations for a number of developmental disability disorders and syndromes.

It is important to note that the absence of an abnormality in genetic testing does not exclude a genetic cause for developmental disability. For individuals in whom no specific cause has been identified, review by a clinical geneticist should be considered every 5 years to determine whether repeat testing using newer testing methods is appropriate (eg for those who had chromosome testing prior to the availability of microarray).