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Panorama Prenatal Test

Panorama Prenatal Test

Test Highlight

Panorama™ Prenatal Test

  

Clinical Use

  • Prenatal risk assessment for Down syndrome, trisomy 18, trisomy 13, and 45,X (Turner syndrome)

Clinical Background

Maternal serum screening is routinely used to determine which pregnancies are at increased risk of a chromosomal abnormality. Although maternal serum screening is considered safe, the sensitivity and specificity are relatively low, and positive results require follow up with invasive testing. Invasive testing, ie, chorionic villus sampling (CVS) and amniocentesis, is the gold standard for prenatal diagnosis of fetal chromosomal abnormalities; however, it is associated with a risk of miscarriage. Plasma has been found to contain cell-free DNA, and maternal plasma contains a relatively large amount of fetal DNA, making it suitable for noninvasive prenatal testing.1 Sequencing of maternal and fetal cell-free DNA is a new alternative that allows noninvasive testing for fetal chromosomal abnormalities.

The American Congress of Obstetricians and Gynecologists recommends cell-free DNA testing be one of the prenatal testing options offered to high-risk women.2 It should not be offered as an option for women with low risk or for women with multiple gestations. Women suitable for testing include those4:

  • Who will be ≥35 years of age at time of delivery

  • At increased risk of fetal aneuploidy based on fetal ultrasonographic findings

  • Who have had a trisomy-affected fetus in a prior pregnancy

  • With a positive maternal serum screening test

  • Who have a balanced Robertsonian translocation with increased risk of trisomy 13 or 21

  • Whose partner has a balanced Robertsonian translocation with increased risk of trisomy 13 or 21

Testing can be performed as early as 9 weeks’ gestation.

Method

The Panorama Prenatal Test evaluates 19,500 single nucleotide polymorphisms (SNPS) in fetal and maternal cell-free DNA. A targeted PCR assay and high-throughput sequencing technology is used to determine fetal risk of trisomies 21, 18, and 13 as well as risk of 45,X (Turner syndrome). The test provides a >99% detection rate for trisomies 21, 18, and 13 at a <0.1% false-positive rate.3 For 45,X, the test provides a 92% detection rate at a <0.1% false-positive rate (n=12).4

Interpretive Information

A patient-specific interpretation is provided on the report. Women with a low risk interpretive comment are considered screen negative and not at increased risk of carrying an affected fetus. A negative screen does not guarantee the birth of an unaffected baby.

Women with a high risk interpretive comment are considered screen positive for the specified disorder and are at increased risk of carrying an affected fetus. Positive results should be followed up with CVS or amniocentesis.2

Limitations

This test has been validated on women with a singleton pregnancy, and of at least 9 weeks gestational age. Tests run prior to 9 weeks have an increased no result rate. This test will not return results on pregnancies conceived with an egg donor or those which used a surrogate and cannot be performed on women who have received a bone marrow transplant. Samples are analyzed for aneuploidy of chromosomes 13, 18, 21, and X only. Abnormalities on other chromosomes or those involving only a portion of the chromosomes tested cannot be excluded. This test may not be able to identify abnormalities or may report a positive result in the presence of mosaicism (which may be confined to the placenta). Gender will be reported as male or female based on presence or absence of a Y chromosome and does not confirm presence or absence of SRY. Pregnancies involving multiples or abnormal ultrasound findings may be better served by other screening or testing options. There is a chance of detecting maternal sex chromosome abnormalities during this testing process (either in full or mosaic form), which, if present, may interfere with the accuracy of the results on the fetal sex chromosomes. Although this test has a high accuracy, the results are not diagnostic. These results should always be interpreted by a clinician in the context of clinical and familial data.

Additional assistance in interpretation of results is available from our Genetic Counselors by calling 866-GENE-INFO (866-436-3463).

References

  1. Vaiopoulos AG, Athanasoula KC, Papantoniou N, et al. Advances in non-invasive prenatal diagnosis. In Vivo. 2013;27:165-170.

  2. Committee Opinion No. 545: Noninvasive prenatal testing for fetal aneuploidy. Obstet Gynecol. 2012;120:1532-1534.

  3. Zimmermann B, Hill M, Gemelos G, et al. Noninvasive prenatal aneuploidy testing of chromosomes 13, 18, 21, X, and Y, using targeted sequencing of polymorphic loci. Prenat Diagn. 2012;32:1233-1241.

  4. Levy B, Demko Z, McAdoo S, et al. Use of targeted sequencing of SNPs to achieve a highly accurate non-invasive detection of fetal aneuploidy of 13, 18, 21, and sex chromosomes. Paper presented at: 33rd Annual Meeting of the Society for Maternal-Fetal Medicine; February 2013; San Francisco, CA.

This test was developed by Natera, Inc., a laboratory certified under the Clinical Laboratory Improvement Amendments (CLIA). This test has not been cleared or approved by the U.S. Food and Drug Administration (FDA).
 Content reviewed 04/2013
 

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