The Illumina test is a non-invasive prenatal test (NIPT) that can identify a pregnancy in which the baby is likely to have a chromosome condition. These conditions are uncommon, do not usually run in the family, and can happen in any pregnancy.
The Illumina test can be requested by your doctor from 10 weeks’ gestation, and we recommend that your doctor arrange for you to have an ultrasound to confirm your gestation, prior to taking your blood sample.
Collecting a mother’s blood sample for the Illumina test poses no threat to the fetus.
The Illumina test routinely screens for these chromosome conditions:
If requested by your doctor, the Illumina test can also screen for:
You also have the option to determine the sex of your baby
The Illumina test is a screening test – it is a test for women who are unlikely to have a baby with a chromosome condition. It is much more accurate than first trimester blood screening and ultrasound tests. This has reduced the need for invasive tests such as chorionic villus sampling (CVS) or amniocentesis, although these will still be required to confirm a high probability result.
NIPT screening for trisomy 21, 18 and 13 – the most common chromosome conditions – provides the highest accuracy. Screening for other syndromes or for fetal sex is reasonably reliable; however, it is not as accurate as the screening for trisomy 21, 18 and 13.
Chromosomal conditions like Down syndrome (trisomy 21) do not typically run in families and can happen in any pregnancy. Although the chance of having a baby with Down syndrome increases with age, most babies with Down syndrome are born to women under 35.2
You must be at least 10 weeks pregnant for this test. Patients who have received bone marrow or organ transplants, or those who have metastatic cancer are not eligible for the test.
There are small fragments of DNA in the mother’s blood that have come from both the mother and the placenta. This is a normal process.
TDL Genetics uses an NIPT assay called Veriseq v2, manufactured by Illumina and processed in our London laboratory. The assay analyses the proportions of the DNA fragments that come from specific chromosomes
If a particular proportion is too high or too low, this indicates that there may be a chromosome condition involving the placenta and, potentially, the developing baby.
Your sample is checked to see if there is sufficient DNA from the developing pregnancy to provide a reliable result. Then, for each condition included on the request form, the report will indicate whether there is a low or high probability of the condition being present.
Results will be sent to the HSCFW in 2–4 business days.
The HSCFW will discuss the report with you and let you know if any other investigations are recommended. In your initial consultation, prior to the test being ordered, we strongly advise that you discuss what you would do with the possible results.
If your report indicates a high probability of a chromosome condition being present, a CVS or amniocentesis procedure can be arranged by your doctor to obtain a definitive result.
No, any screening test carries a chance of a ‘false negative’ however the chance of this happening with the Illumina test is much lower than with conventional screening for Down syndrome and other chromosome conditions.
No, not necessarily. It means that there is a higher chance that your baby may have a chromosome condition, and you will be offered the option of amniocentesis to assess the chromosomes directly. You will be offered support and counselling to help you reach that decision.
This test can also be applied to twin pregnancies but is not suitable in the case of a vanishing or demised twin.
The sex of twins will be reported as one result. If male, one or both of the twins will be male. If female, both twins will be female.
Two out of 100 women will require a repeat test. Patients will not be charged if we are unable to obtain a result.
On rare occasions, it is not possible to issue an Illumina test result. This is usually due to the complex biology of pregnancy rather than a failure of the test method.
If the Illumina test cannot provide an assessment for the three most common chromosome conditions (trisomy 21, 18 and 13) after one collection of a blood sample (or two, if recommended by the laboratory), you will not be charged.
The Illumina test assay used by TDL Genetics – VeriSeq NIPT Solution v2 – is not validated for use in pregnancies with more than two fetuses, nor in cases of fetal demise, mosaicism, partial chromosome aneuploidy, triploidy, translocations, maternal aneuploidy, transplant or malignancy. VeriSeq NIPT Solution v2 does not detect neural tube defects. Certain rare biological conditions may also affect the accuracy of the test.
For twin pregnancies, HIGH PROBABILITY test results apply to at least one fetus; male test results apply to one or both fetuses; female test results apply to both fetuses.
Due to the limitations of the test, inaccurate results are possible.
A LOW PROBABILITY result does not guarantee that a fetus is unaffected by a chromosomal or genetic condition. Some fetuses without a trisomy or chromosomes anomaly may have HIGH PROBABILITY results. In cases of HIGH PROBABILITY results and/or other clinical indications of a chromosomal condition, confirmatory testing is necessary for diagnosis.
Please note that we are led by a team of highly skilled specialist doctors that offer diagnosis and treatment of complications which may arise in unborn babies. All your scans will be performed by our experienced fetal medicine consultants. We do not offer scans performed by sonographers or fellows. The service we provide by consultants offer screening, diagnosis and management of your pregnancy to the highest standards.
Includes pre-test genetic counselling and Illumina test.
This option applies only if you have had a scan recently. We will ask you to bring a recent scan report (performed within 2weeks) with the measurements of the baby.
Includes an ultrasound scan appropriate for gestational age by our consultant specialist followed by the Illumina blood test.
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Thank you so much for all of your help and support.”
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