Microarray
What is a microarray?
A chromosome microarray (CMA or molecular karyotype) is a powerful tool used to look at very small changes in our genetic information that may affect health and/or normal development.
These small changes in DNA are known as copy number variants (CNVs). A CNV is a small piece of extra or missing DNA (duplications and deletions).
Everyone has CNVs in their DNA and most do not affect health. However, some CNVs are known or highly suspected to affect health and development.
This page talks about microarray use in the postnatal paediatric setting. Microarray's can also be used for prenatal diagnosis.
Use in paediatrics
A microarray is the recommended first line genetic test for developmental delay (DD), intellectual disability (ID) and autism spectrum disorders (ASD). A microarray detects the likely cause of a range of developmental concerns in about 15% of referrals.
CMA however, does not identify fragile X syndrome (FXS), a common cause of intellectual disability. Therefore, a DNA test for FXS must be ordered alongside a CMA.
A Medicare rebate is available for both tests and testing can be performed using saliva instead of blood.
Miller, D.T., et al, Consensus statement: Chromosomal microarray is a first-tier clinical diagnostic test for individuals with developmental disabilities or congenital anomalies. Am J Hum Genet. 2010; 86: 749–764
Battaglia et al., 2013 Confirmation of chromosomal microarray as a first-tier clinical diagnostic test for individuals with developmental delay, intellectual disability, autism spectrum disorders and dysmorphic features. Eur J Paediatr Neurol. 2013 Nov;17(6):589-99)
What does this test look for?
A microarray replaces most tests looking for CNVs (e.g. microdeletion and microduplication syndromes), but does not replace all other genetic investigations. Tests with complex genetics, like fragile X syndrome, need to be requested and performed separately.
When a CNV is identified in a child, parental testing is often requested as a next step. This can help to determine whether a CNV has been inherited, and in some cases, can assist the lab in interpreting the possible significance of the CNV.
If you aren’t sure if microarray is the most appropriate test for your patient, or why parental testing has been requested, please contact our paediatric genetic counsellor.
How do I arrange this test?
Microarray testing is typically arranged through a paediatrician, a clinical genetics service or in some cases, a GP. A completed test request form is required.
Alternatively, a paediatric microarray can be requested via our online test request system.
Testing can be performed on blood or saliva. You can also arrange for a saliva kit to be sent directly to your patient’s home address.
See full test and specimen requirements >