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A B C D E F G H I J K L M N O P Q

Test Identifier Information

 
Registration CodeCTGN
Method

 QF-PCR is a molecular genetic technique that selectively amplifies certain regions of genomic DNA using fluorescently-labelled primers which bind to specific regions of chromosomes 13, 18, 21, X and Y in fetal DNA. QF-PCR products are run on a capillary electrophoresis system and separated by size, so that each peak is the product of the amplification of a specific probe. The fluorescent signal intensity is measured digitally to determine the copy number for each target sequence.

QF-PCR is widely used for quantitative diagnosis of the three most common viable autosomal trisomies: trisomy 13 (Patau syndrome), trisomy 18 (Edwards syndrome) and trisomy 21 (Down syndrome). The test kit also includes X and Y chromosome markers and the TAF9L marker for the determination of sex status.  

As QF-PCR genotypes the sample, it can also help to resolve mixed cell populations and may identify maternal cell contamination, mosaicism, twin pregnancy and chimerism.

 

 

 

 

 

 


Diagnostic Use / Indications

QF-PCR is employed at CHL as an aneuploidy screen for trisomy 21, 18, 13, monosomy X and triploidy in fetal tissues.  If the QF-PCR yields a normal result, microarray testing will be performed.  

Indications for QF-PCR+microaray:
Recurrent miscarriage (defined as ≥ 3)
Abnormalities on ultrasound or abnormal fetal phenotype
Family history of a chromosomal rearrangement
 
Specimens with no clinical indications or indications not meeting the above criteria, will have DNA extracted and stored only; no testing will be performed.  If testing is required, clinical information must be supplied.  
 
Suspected molar pregnancies will still be routinely tested by FISH from FFPE specimens. This testing may evolve to QF-PCR in the future.
 
External Price$0.00(Exclusive of GST)
  

Specimen Collection

 
Pre-Testing Requirements

 Appropriate counselling where the implications for the microarray test and the expected results can be discussed.  It is necessary to complete a specific patient consent form prior to ordering a microarray.  Patient information leaflet and consent forms are available under MICROARRAY and also the Specimen Requirements tab in CHL Test Manager. 

Include relevant clinical information, gestational age, mother's NHI# and fetal sex (if known) on request form.

 

 

Specimen Collection Protocols

Sterile specimen, must not be in formalin, with/without RPMI Tissue Transport Medium (order from CHL Patient and Client services 03 364 0484, open 09.00-17.00, Mon-Fri. See Specimen Requirements tab, Test Manager). 

Products of Conception (POC) and Placenta - placental villi or recognisable fetal tissue (approx. 0.5 x 0.5cm). Please also send 2ml EDTA (purple top) blood from the mother for maternal cell exclusion testing and send together with the POC.  

A paternal specimen is usually not necessary and will be requested if required.

Fetal Tissue (post mortem) -  Two different fetal tissues. Cartilage and pericardium are preferable. Please identify the tissues clearly on the request form.  Spleen or skin is not generally suitable for microarray testing. 

Fetal Blood - 1-2mls (2-3 paediatric tubes)

 

Patient SpecimenFetal tissue or placental villi
Sample Delivery to LabLab receives samples 24/7. Send without delay
  

Instructions for Referral to CHLabs

 
Aliquot InstructionsDO NOT FREEZE. DO NOT EXPOSE TO FORMALIN.
Aliquot Transport to CHLRoom temperature
  

CHLabs Laboratory

 
DepartmentHaematology - Cytogenetics
Contact Details Email Email
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Contact Phone Number03 364 1425
Turnaround TimeQF-PCR within 10 days (Microarray within 28 days)
Reference Interval

 Comment in the report

Interpretation

 Comment in the report

Uncertainty of Measurement

QF-PCR can identify 20-30% of cases of mosaicism, which is comparable to karyotyping and FISH.

Additional Information

QF-PCR will not detect balanced structural rearrangements or distinguish between aneuploidy caused by a nondisjunction event or an unbalanced rearrangement. 

In 5-10% of specimens no result will possible due to the presence of significant maternal cell contamination, poor fetal DNA quality or where no clearly identifiable villi or fetal tissue is detected.  In these cases, no further testing will be initiated.

If aneuploidy or triploidy is detected, microarray testing will not be performed.   

 

 


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