Cascade prenatal testing (by QF-PCR, array) excluding maternal contamination

Test covered by the reimbursement:

YES

Gender:

Woman

Material:

Chorionic villi, Amniotic fluid …

Material:

Chorionic villi | Chorionic villi, min. 30 mg tissue in a microtube (Eppendorf type)

Storage after examination: week after the report is issued 2 – 8°C

Amniotic fluid | 3x 10 ml of amniotic fluid in a tube

Storage after examination: week after the report is issued 2 – 8°C

Cord blood | 2–3 ml of cord blood in EDTA

Storage after examination: week after the report is issued 2 – 8°C

Isolated DNA from chorionic villi | 30–100 ng/μL of isolated DNA from chorionic villi in a microtube (Eppendorf type)

Storage after examination: stored in a DNA archive without restriction 15°C

Isolated DNA from amniotic fluid | 30–100 ng/μL of isolated DNA from amniocentesis in a microtube (Eppendorf type)

Storage after examination: stored in a DNA archive without restriction 15°C

Isolated DNA from cordocentesis | 30–100 ng/μL of isolated DNA from cordocentesis in a microtube (Eppendorf type)

Storage after examination: stored in a DNA archive without restriction 15°C

DNA isolated from cultured cells | 30–100 ng/μL of isolated DNA from cultured cells in a microtube (Eppendorf type)

Storage after examination: stored in the DNA archive 15°C

Quick test description:

Cascade aneuploidy testing of material after invasive prenatal examination using QF-PCR and array methods, excluding maternal contamination. This can be supplemented by foetal karyotyping, if necessary.

Test details:

During the cascade prenatal testing, the sample is first tested by QF-PCR for rapid determination of chromosome aneuploidy associated with severe genetic conditions and syndromes. For amniotic fluid and chorionic villi, a standard set of markers for chromosomes 13, 18, 21, X and Y is used. This is performed by analysis of polymorphic STR markers, including the PCR technique and capillary electrophoresis. The method uses multiplex QF-PCR to multiply multiple fluorescently labelled DNA fragments of specific STR markers on the chromosomes tested in a single reaction. After amplification, DNA fragments are then separated, detected and analysed using capillary electrophoresis and appropriate software on a genetic analyzer. Fragments of individual STR markers are specified by the length and type of fluorescence labelling. Each fluorescently labelled DNA fragment appears as a peak with a certain height/area that is proportional to the amount of DNA.

The QF-PCR method is characterised by several sets that differ in the STR markers used and suitability for use: a standard set of markers is used for the examination of chromosomes 13, 18, 21, X and Y in DNA from chorionic villi, amniotic fluid or aborted foetal tissue, or maternal blood to exclude maternal contamination. In the case of insufficient informativeness of the STR markers and to verify the findings in the samples tested, marker supersets for these chromosomes are used. In the case of aborted foetuses (SAB), SAB-supersets I and II are used to test chromosomes 2, 4, 6, 7, 14, 15, 16 and 22 to exclude these most common aneuploidy.

To exclude maternal contamination (especially in chorionic villi), the maternal peripheral blood is tested with the same set of markers. In the case of a normal QF-PCR result, the sample is further examined by SNP array for genome-wide detection of submicroscopic chromosomal aberrations. If the result of any of the methods is ambiguous (possibly mosaic or chromosomal remodeling), the cascade is complemented by karyotyping.

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