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Invitae NIPS for Twin Pregnancies (chromosomes 13, 18, 21)

Test description

Invitae Non-invasive Prenatal Screening (NIPS) for Twin Pregnancies analyzes whether a twin pregnancy is at increased risk for the chromosome disorders listed below.

All NIPS reports include analysis of chromosomes 21, 18, and 13 and assess the risk of the following trisomies:

  • Trisomy 21 (Down syndrome)
  • Trisomy 18 (Edwards syndrome)
  • Trisomy 13 (Patau syndrome)

Y chromosome analysis can also be included to determine if at least one twin is male. However, the presence of the Y chromosome cannot differentiate between one male twin or two male twins.

To include Y chromosome analysis in your order, please select the checkbox below.

Please see the Disorders Tested section for more information about these chromosome disorders.

Order test

Invitae NIPS for Twin Pregnancies (chromosomes 13, 18, 21)
Add-on for Presence of Y Chromosome (to infer predicted fetal sex)

Analysis of the presence of the Y chromosome can be added at no additional charge.

Alternative tests to consider

DisorderChromosomeDescriptionPrevalence
Down syndrome Trisomy 21 Although some pregnancies with trisomy 21 end in pregnancy loss, trisomy 21 often can lead to live birth. Individuals with trisomy 21 have variable physical features and intellectual disability. Some of the common features of trisomy 21 include heart defects, low muscle tone, and differences in facial features. In addition, cognitive impairment can range from mild to severe. People with Down syndrome have a higher risk for certain medical conditions, such as hearing problems, thyroid problems, childhood leukemia, and Alzheimer’s disease. People with Down syndrome may require supervision throughout their lives. However, many people with Down syndrome are increasingly attending school and holding jobs. Many individuals with Down syndrome live into adulthood. Trisomy 21 is the most common chromosome abnormality, occurring in 1 in 700 to 800 live births.
Edwards syndrome Trisomy 18 Although many pregnancies with trisomy 18 result in miscarriage or stillbirth, trisomy 18 can result in livebirth. Individuals with trisomy 18 have severe intellectual disability and abnormalities involving multiple organs. Some of the common fea-tures of trisomy 18 include heart defects, brain abnormalities, muscu-loskeletal problems, cleft lip and palate, and low birth weight. Although less than 10% of babies with trisomy 18 will live past 1 year of age, some people with this condition can live years or even decades. Trisomy 18 occurs in 1 in 6000 to 8000 live births.
Patau syndrome Trisomy 13 Although the majority of pregnancies with trisomy 13 result in miscarriage or stillbirth, trisomy 13 can result in live birth. Individuals with trisomy 13 have severe intellectual disability and abnormalities involving multiple organs. Some of the common features of trisomy 13 include heart defects, omphalocele, brain abnormalities such as holoprosencephaly, cleft lip and palate, and other features. Although less than 10% of babies with trisomy 13 will live past 1 year of age, some people with this condition can live years or even decades. Trisomy 13 occurs in approximately 1 in 12,000 live births.

Test Location
Invitae NIPS will be sent out by Invitae to Verinata Health, Inc, a wholly owned subsidiary of Illumina, Inc., which will then perform the screen and send the report to Invitae.

Test Method
Nucleic acid extraction, DNA sequencing, and analysis of sequencing results to determine fetal aneuploidy.

Invitae NIPS is validated for aneuploidy of 21, 13, 18, X, and Y in twin pregnancies, with gestational age of at least 10 weeks 0 days.

Limitations
This is a screening test that looks only for specific chromosomal abnormalities. A normal result does not eliminate the possibility that the pregnancy is associated with other chromosomal or subchromosomal abnormalities, birth defects, genetic conditions, or other conditions, such as open neural tube defects or autism.

There is a small possibility that the test results might not reflect the chromosomes of the fetus, but may reflect chromosomal changes of the placenta (confined placental mosaicism, CPM) or of you (maternal chromosomal abnormalities). Examples include maternal XXX, sex chromosome status, or benign and malignant maternal neoplasm. CPM may be associated with a higher chance for pregnancy complications or for uniparental disomy (UPD), which may affect the growth and development of the fetus. Some of these rare chromosomal aneuploidies may only occur in mosaic form. Clinical consequences depend on the chromosome involved and can not be predicted prenatally. This test, like many tests, have limitations, including false negative and false positive results. A negative test result does not eliminate the possibility of chromosomal abnormalities for the tested chromosomes or microdeletions.