Southern Cross Pathology Australia
Provision
of Prenatal Diagnosis (DNA testing)
1
Guidelines
This
laboratory provides prenatal DNA testing for pregnancies at risk for severe
thalassaemia/haemoglobinopathies and for haemophilia A & B.
Prenatal
genetic testing can only be performed when prior DNA testing has established the
parental genotypes (ie. mutations or linkage markers).
NPACC, Laboratory Accreditation
Standards and Guidelines for Nucleic Acid Detection techniques
2000 state that "prenatal DNA testing requires formal consent, pre- and
post-test counselling, confidentiality procedures and close dialogue between
laboratory and clinical services.
2
Procedure for notification for CVS DNA testing
2.
Arrange notification of the procedure – this will usually be done by
those providing genetic counselling.
The
issues that need to be addressed with respect to notification are:
·
The
laboratory, SCPA Clinical Genetics 03
9594 3398, should be informed no later than two weeks prior to the procedure
that a CVS is to be booked .
Note:
The
scientist in charge will check that all the necessary parental testing has been
completed and documented, and that control DNA samples are available for the
required testing.
The laboratory will confirm that testing
can be done. If not, the procedure
may need to be postponed whilst counselling and parental testing are undertaken.
·
Details of the CVS procedure must be forwarded in writing to the
laboratory using the attached NOTIFICATION OF CVS FOR PRENATAL GENETIC TESTING
form.
·
The cytogenetics laboratory to which the sample will be sent for
dissection (see 4) should also be
notified.
3 Timing of CVS
procedure
A
CVS procedure for DNA testing should be performed in the morning and no later in
the week than Thursday.
Note:
The Clinical Genetics Laboratory should receive the dissected CVS
material (see 4) the same day to
ensure that the quality of the DNA extracted for testing is not compromised.
4
Processing of samples by Cytogenetics
Chorionic
Villus Biopsy or amniocentesis samples must be processed* by a cytogenetics
laboratory that routinely handles samples for prenatal DNA testing. The preferred laboratory is SCPA
Cytogenetics Tel 9594 3472/74
Note:
*CVS samples are dissected to remove contaminating maternal tissue or, if
necessary, cultured to increase the yield.
In the case of Haemophilia prenatal samples, the sex of the foetus is
determined prior to DNA testing. Amniotic
fluid cells are cultured until a confluent 25cm2 flask is available
(usually 1-2 weeks).
The Clinical Genetics laboratory liaises with the Cytogenetics laboratory regarding the material required.
5
Cancellation of the procedure
If
a prenatal collection procedure is postponed or cancelled the Clinical Genetics
laboratory as well as the Cytogenetics laboratory should be informed.
6
Reporting of prenatal DNA testing results
Prenatal
testing reports are sent to the referring Genetics Clinic or in the case of
private patients only to the referring doctor.
The results will usually be available within two weeks unless otherwise
indicated.
7 Genetic counselling for Thalassaemia/haemoglobinopathies
If you wish to arrange for a client to receive genetic counselling prior to a prenatal test, this can be done by contacting:
Monash
Medical Centre Medical Therapy/Thalassaemia Unit
Phone 9594 2756
Royal
Women’s Hospital Genetics Clinic Phone
9344 2121
Mercy
Hospital Genetics Clinic
Phone 9270 2394
8 Prenatal Genetic Testing request form
To print a copy of a prenatal genetic testing request form click on prenatal.pdf
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