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Microarray (parental)

Also known as: Follow-up microarray, Parental SNP array, Parental CGH microarray, Parental microarray, Parental Molecular Karyotype

Test category:

Paediatric - Congenital disorder

Use of test

Purpose:

Microarray analysis can detect submicroscopic deletions and duplications of genetic material across all chromosomes.

Parental testing may be suggested to determine whether a deletion or duplication has been inherited or has arisen de novo in an affected child. This can give information regarding the clinical significance of a detected deletion or duplication, and/or information regarding recurrence risks. 

Utility:

Parental testing may be suggested to assist in determining pathogenicity of a variant of uncertain clinical significance.

The presence of a pathogenic abnormality in a proband provides specific diagnostic and prognostic information. Parental and further family studies may clarify the recurrence risk in relatives.

Ethical considerations:

This is an assay for mutations which may be heritable or de novo. It may raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient. Use of the consent form (below) is not mandated, but could be used to guide the discussion with the patient.

Consent form:

Download the Sonic Genetics consent form.

Methodology:

The relative amounts of genetic material from hundreds of thousands of small regions from all chromosomes are measured. Deviations from the expected values can identify deletions and duplications.

Sonic Genetics uses a single nucleotide polymorphism (SNP) microarray, which provides additional genotype information compared with CGH microarray. SNP microarrays can identify large regions of homozygosity, which may be useful in detecting uniparental disomy or an increased likelihood of a recessive disorder.

Requesting the test

Ordering:

This test can be requested by any medical practitioner.

Sample required:

2-5 mL blood in EDTA or lithium heparin. Specimens may be collected by the requesting practitioner or at any Sonic Healthcare collection centre (see link below).

Buccal swabs are available on request, please contact the laboratory if this method of collection is required.

To help ensure the quality of the test, a genetic test should be done with a dedicated sample whenever possible i.e. a sample collected specifically for that test rather than a sample that is used for multiple tests.

We recommend that the patient or another adult check the labelling of request forms and sample tubes. 

>Link to Sonic Healthcare collection centres

Special instructions:

Please include details of any clinical abnormalities in the patient being tested, and the results of chromosome or array studies in relatives.

Turnaround time:

3-4 weeks.

Price:

This test has a Medicare rebate which, subject to the requirements of the Medicare descriptor being met, may cover all or part of the cost.

Note that microarray and karyotype analyses cannot both be rebated on the same test episode.

Rebate:

The Medicare details, including descriptor and schedule fee, are listed under MBS item 73289.