BabySEQ evaluates chromosomal and placental chromosomal disorders in the baby, screening and reporting fetal growth retardation, preeclampsia in pregnancy, and other pregnancy risks.
1- BABYSEQ ALL CHROMOSOMES PACKAGE
It screens for numerical increase or decrease (aneuploidies) of 46 Chromosomes (23 pairs) of the fetus by bioinformatic analysis.
A basic panel should be studied in multiple pregnancies because the reliability is slightly lower than the literature data in terms of microdeletion syndromes, but a clear rate has not been given.
2- BABYSEQ ALL CHROMOSOMES + MICRODELETIONS PACKAGE
It scans for numerical increases or decreases (aneuploidies) of 46 chromosomes (23 pairs) of the fetus, as well as microdeletions and microduplications.
There are 89 microdeletion and microduplication syndromes in the report, but we also report microdeletions and
microduplications detected in a patient-specific region.
Opinions of our center:
The population frequency of chromosomal diseases is reported as 1/400. Depending on the type of chromosomal diseases, 50-90% of them show findings on ultrasound. However, some patients do not show any findings in ultrasound, double scan, triple and quadruple scan.
The frequency of microdeletions has recently been evaluated as 1/1500. The most important problem is that only 1/3 of these diseases give information on ultrasound.
In both groups of diseases, the risks of mental retardation and organ abnormalities increase depending on the type of disease.
Screening tests are for the detection of diseases that are difficult to detect. Ideally, large screening tests should be performed. This situation increases the probability of screening test-associated amniocentesis, CVS, and disease diagnosis.
Definitions
• cff-DNA: (Cell-Free Fetal- DNA) (Extracellular fetal DNA)
• NIFT: Non-Invasive Fetal Screening using of-DNA
• NIPT: Non-Invasive Prenatal Screening using cff-DNA
• Positive predictive value: it is the actual probability of getting sick in the population with a (+) result in the test population. It is affected by prevalence and specificity. (90-92% value in NIPT tests)
• Negative predictive value: the probability that those with a (-) result in the test population are not sick for the disease under investigation. It is affected by prevalence and sensitivity. (Value in NIPT tests 98-99%)
• Mosaicism limited to the placenta: It is the case of a chromosomal anomaly in the placenta when the fetal chromosomes are normal. When
NIPT is also present in 13, 18, 21, non-X, and Y chromosomes, it contributes to the calculation of fetal and maternal risk. For this evaluation, it is necessary to analyze all chromosomes.
What does NIPT provide?
• It provides the evaluation of placental chromosomal structure.
• If this test is abnormal, if there is a compatible result in the amniotic fluid, it enables the diagnosis of fetal chromosomal diseases.
• If the amniotic fluid is incompatible with this test, it enables the diagnosis of mosaicism limited to the placenta.
• If there is an increased risk of IUGR and preeclampsia, it provides detection.
• Screening of all chromosomes is required for these diagnoses.
• Microdeletion syndromes are seen with a frequency of 1/2500 and the rate of detecting findings with ultrasound is 30%. It provides the detection of an important part of these diseases.
• If evaluated correctly, it increases the chance of a diagnosis of diseases such as uniparental disomy that cannot be diagnosed in amniocentesis.
• In summary, it contributes to studies on fetal and maternal health.
These are the benefits that can be achieved with accurate clinical genetic evaluation.
What does it not provide?
• It cannot diagnose all chromosomal diseases.
• It cannot diagnose all genetic diseases.
• Except for chromosomal diseases, it is not a diagnostic or screening tool for genetic and non-genetic diseases.
When is it done?
• After the 11th week
• If possible, after NT measurement,
• It can be applied if there is no family history of genetic disease.
The society that can be scanned
• It can be applied to all pregnant women as a screening test.
When is it DEFINITELY not done?
• Positive family history that raises suspicion of genetic disease
• NT increase (NT≥3.5 mm)- If the person does not want the interventional procedure definitively, NT thickness can be performed not only for diagnosis but also for risk assessment in terms of chromosomal diseases.
• Finding on ultrasound
• High risk (1/100 and above) in biochemical screening tests (double, triple, or quadruple test)- If the person does not want the interventional procedure definitively, NT thickness can be performed not only for diagnosis but also for risk assessment in terms of chromosomal diseases.
• Partial mole
What if the NIPT is POSITIVE (Abnormal)?
• Preferably, the result should be confirmed by amniocentesis. Sometimes CVS or CVS+ amniocentesis samples can be used with the joint decision of the genetics and obstetrician.
• It can be used for confirmation by consulting a CVS geneticist in pregnancies before 15 weeks. If CVS is desired, FISH or direct preparation should not be performed together.
• NIPT is a SCREEN test. It doesn't identify. It only determines risk. TREATMENT OR PREGNANCY TERMINATION SHOULD NOT BE DONE WITHOUT CONFIRMATION.
• Refer the patient for Genetic Counseling.
What if the NIPT is NEGATIVE (Normal)?
• Pregnancy follow-up continues.
• If there is an additional risk in USG or other evaluations in the following weeks, consult a geneticist.
• As with all other medical tests, NIPT is not a 100% reliable test.
What if results from NIPT are not available?
Medical Reasons;
• If there is no test failure due to reasons such as maternal obesity, the frequency of aneuploidy and triploidy per case is 2.5 times higher in test failures.
• When the blood is requested again, the risk increases even more if the result is not obtained from the second study.
Technical Reasons;
• Low fetal fraction
• Sampling, storage, and transport problems
• Hemolysis
Suggestions;
• You can take blood again and send a sample.
• Blood must be taken with a Vacutainer needle.
• In cases where the risk increases, an interventional procedure (Amniocentesis or CVS) can be recommended to the family by stating that the risk increases.
• It is the most appropriate solution for the family to present both information to the family and make a decision.
• The patient can apply to our Center for Genetic Counseling.
Causes of NIPT false test result
• Maternal Mosaicism
• Fetal Mosaicism
• Mosaicism limited to the placenta (frequency of mosaicism limited to placenta ~ 1.5% in live births)
• Vanishing twin- vanishing twin
• Maternal Cancer
• Triploidy may not be detected in whole genome analysis-based methods.
• SNP-based methods increase the risk of error in consanguineous marriages.
• BabySEQ is a whole genome analysis-based method.
Method selection
• Methods show similar success in Down syndrome, Trisomy 13, and Trisomy 18. However, recent publications show those whole genome-based methods have better positive and negative predictive value.
• If triploidy is suspected, an interventional procedure should be performed. If the family does not accept the interventional procedure, SNP-based methods should be used.
• The margin of error in the evaluations regarding the sex chromosome is higher than the other chromosomes.
• Whole genome-based methods should be used in consanguineous marriages (including those from the same village or town).
• It is a more suitable method based on the whole genome in twin pregnancies.
• Centers that conduct tests in the country should be preferred, as transportation time is important.
Microdeletion scan
• Relatively more successful screening can be done with the whole genome-based method.
• Procedures such as pregnancy termination should not be performed without confirmation by amniocentesis or CVS.
Multiple Pregnancies
• Reliability drops slightly.
• NT screening is important in twin pregnancies.
• It is a more suitable method based on the whole genome in twin pregnancies.
For Physicians and Patients
Genetic Consultation via Whatsapp: +90 533 727 25 47
Genetic Counseling by Phone: +90 312 428 48 14