In our lab, we have decided aboout a year ago to confirm all molecular
genetic analysis performed by reanalysing a second, independent sample in an
independent run. This is not a large problem when dealing with genotyping as
eg HFE or CYP2D6; but when searching for unknown mutations by using a
scanning analysis (eg DGGE) or direct sequencing for the analysis of the
porphyria genes, it is a major task.
the reason why we have chosen this strategy is, that we believe that most
molecular genetic analyses are performed once-in-a-patients-life and
therefore faults may never be displayed. By running the analysis twice on
two indenpendent bloodsamples, we expect to minimise errors due to
patientidentification, labelling of samples etc. and to minimise analytical
errors.
In general, we believe that a false negative result should be avoided as
well as a false positive result - that is why we also reanalyse samples in
which we have not displayed a mutation.
If the first sample is referred to our dept. without a previous contact to
the referring clinician, we simply inculdes (in Danish) in the description
of the result send to the clinician following passus: "As this kind of
analysis ususlly is a "once-in-a-lifetime-test", we recommend that a new
EDTA-blood sample from the patient is send to our department. The analysis
of this new sample is performed without extra costs. Until this sample has
been reanalysed, the answer shall be looked on as preliminary only". In the
cases of mutation analysis of teh BRCAI and II, no answer is send to the
clinician before the second sample has been analysed. Only a limited number
of clinicians (acutally mostly Clinical Geneticists) requires these analysis
so the setup is not really complicated as they can tell the patient that two
samples shall be drawn and analysed at separate occations.
Kind regards
Niels Erik Petersen
======================================
Niels Erik Petersen, MD, PhD
Consultant, associate professor
Department KKA, Clinical Biochemistry and Clinical Genetics
Odense University Hospital
DK-5000 Odense
Tlf: +45 6541 2873
Fax: +45 6541 1911
-----Original Message-----
From: This list is an open discussion list for the academic community
working in [mailto:[log in to unmask]]On Behalf Of dr.
C.H.H. Schoenmakers
Sent: 9. marts 2001 09:58
To: [log in to unmask]
Subject: confirmation of positive PCR results
Dear colleagues,
Some of the labs that perform our PCR-analysis advise to confirm a
positive result by sending in a second independent sample. I know
of course what offers maximal security but wondered how this is
handled in practice. I would like to know if everybody confirms
every positive result of every test or if restrictions in confirmations
are made. Thanks.
Christian
======================================
dr. C.H.H. Schoenmakers, clinical chemist
Department of Clinical Chemistry
Elkerliek Hospital
P.O. box 98
5700 AB Helmond
The Netherlands
(+)31-492-595694 (tel)
(+)31-492-595691 (fax)
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