Sample requirements

For all molecular diagnostic testing, a blood sample is required. Blood samples should be collected in EDTA tubes .

Blood samples collected in Sodium or Lithium Heparin may later be resistant to digestion with some enzymes and/or PCR amplification.

Two 10ml EDTA tubes (20ml total) are requested from adults and a minimum of 5ml is required from children and individuals who are difficult to bleed.

Volumes of blood smaller than 5ml may be acceptable however, results from such samples cannot be guaranteed and a rebleed may be requested.

Small volumes of blood should be placed in an appropriately sized collection EDTA tube.

An appropriately filled out request form must accompany the blood specimen. Information on the request form must include:

• Patient name
• Patient date of birth
• Requesting doctor details (including address for reports to be sent)
• Clinical details
• Test requested

Unlabelled samples will not be accepted.

Incomplete request forms may result in delay of results.

Sample requirements - prenatal diagnosis

Prenatal diagnosis of high-risk pregnancies is performed at approximately 10 weeks on chorionic villus samples (CVS). For molecular genetic prenatal diagnosis a CVS sample is required.

Prior notification of CVS sampling is essential.

Any CVS sample sent to the laboratory must be accompanied by a signed consent form before testing can proceed.

A minimum of 5mg wet weight is required for molecular diagnosis based on PCR only (eg D/BMD, SMA, sexing, linkage analysis).

At least 10mg are necessary for diagnoses involving Southern analyses eg. FRAXA and DM.

Smaller CVS samples will result in a delay in molecular genetics results. A result cannot be guaranteed and a repeat specimen may be requested.

Amniotic fluid samples are generally not appropriate for prenatal molecular genetic studies. If this is the only sample available discussion with the laboratory is required before amniocentesis.

These are Class B tests and are subject to testing under National Pathology Accrediation Advisory Council (NPAAC) guidelines (2000).

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