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  • THE IMPORTANT ROLE OF GENETIC SCREENING Making the best decisions for you and your family

  • MORE INFO

    Screening overview Carrier screeningGenetic screening Noninvasive prenatal screening

    Noninvasive prenatal screening Chromosome conditions

    Serum screening Hormone and protein levels associated with birth defects

    Ultrasound Anatomical abnormalities

    Carrier screening Inherited conditions

    A VARIETY OF SCREENING METHODS ARE USED TO DETERMINE RISK DURING PREGNANCY

  • Complementary Screens During Pregnancy • Several different types of screening tests are offered during

    pregnancy

    • Each is performed with the goal of assessing for risks and complications in the pregnancy

    • Some routine screening tests done during pregnancy include: carrier screening, noninvasive prenatal screening using cell-free DNA, ultrasound and maternal serum screening

    • Screening tests are done at different points during pregnancy and for different purposes

    Screening vs. Diagnostic Tests • Screening tests are different than diagnostic tests

    • Screening tests do not give definitive answers. Instead, they provide information about whether there is an increased chance of a problem being present

    • Diagnostic tests, such as chorionic villus sampling (CVS) or amniocentesis, are available to provide definitive information

  • MORE INFO

    Carrier screening and noninvasive prenatal screening, two genetic screens done early on, can inform the care of your pregnancy and baby. Noninvasive prenatal screening can help avoid the need for invasive diagnostic tests (indicated by below).

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    Screening overview Carrier screeningGenetic screening Noninvasive prenatal screening

  • Carrier Screening • Ideally done preconception, but can be done during pregnancy

    • Looks for irregularities, called mutations, in the mother’s and/or father’s genes that can be passed down to a child

    • In most cases both mother and father need to be carriers for the same condition for their children to be at risk of developing symptoms

    Dating Scan (Ultrasound) • Usually done at first prenatal visit

    • Sound waves are used to visualize the developing baby (this is completely safe!)

    • Confirms a heartbeat

    Anatomy Scan (Ultrasound) • Performed at ~18-20 weeks

    • Used to check normal growth and development of the baby

    Noninvasive Prenatal Screening • Done using a standard blood draw from the mother’s arm

    as early as 10 weeks

    • Assesses risk for chromosome conditions, including Down syndrome and other more severe conditions

    • Chromosome conditions generally happen by chance, instead of being inherited from the parents

    1st and 2nd Trimester Maternal Serum Screening • Performed at ~10-14 weeks and then at ~15-20 weeks

    • Estimates the chance for chromosome conditions and birth defects of the spine

    – Looks at a variety of proteins in the mother’s blood – May include a nuchal translucency ultrasound

    • Screening tests are different than diagnostic tests

    • Screening tests do not give definitive answers. Instead, they provide information about whether there is an increased chance of a problem being present

    Screening Tests

    Chorionic Villus Sampling (CVS) • Performed between 10 and 14 weeks

    • Using ultrasound guidance, a small sample of the placenta is removed and analyzed

    • There is a risk of miscarriage with this procedure, but this risk is less than 1% (less than 1 in 100)

    Amniocentesis • Generally performed between 16 and 22 weeks

    • A small sample of fluid is taken from the uterus without touching the baby

    • Fetal cells in the fluid are analyzed to look for certain kinds of abnormalities, while the fluid itself is analyzed for certain proteins

    • There is a risk of miscarriage with this procedure, but this risk is less than 0.5% (less than 1 in 200)

    Invasive Diagnostic Tests • Diagnostic tests, such as chorionic villus sampling (CVS) or amniocentesis, are available to provide definitive information

  • MORE INFO

    GenesCells Chromosomes DNA

    Noninvasive prenatal screening

    Determines risk of baby having a chromosome condition

    Carrier screening Determines baby’s risk of having a condition passed down from

    the mother and father

    GENETIC SCREENS ARE LIKE ULTRASOUNDS FOR DNA

    Screening overview Carrier screeningGenetic screening Noninvasive prenatal screening

  • Cells • The human body contains trillions of cells

    • Cells in different parts of the body have different functions, but with only a few exceptions every cell contains the same genetic information

    DNA • Chromosomes are made up of tightly packed DNA

    • DNA consists of bases named A,C,T and G

    • DNA is like the blueprint for a person

    Chromosomes • Most of the genetic information in each cell is located in

    the nucleus. It is organized into compact chunks called chromosomes

    • Typically cells contain 46 total chromosomes, organized into 23 pairs

    • One member of each pair of chromosomes comes from the mother, and the other comes from the father

    • Noninvasive prenatal screening is used to determine if by chance there are any extra or missing chromosomes in a pregnancy

    Genes • Small segments of DNA that act as the recipes for individual

    proteins are called genes

    • The genes babies inherit from their parents pass along family characteristics like hair and eye color. Sometimes they also pass on genetic diseases, even if the parents don’t have any symptoms

    • Carrier screening is used to determine if prospective parents carry mutations in genes that could cause an inherited condition

  • MORE INFO

    Screening is also available for: Sex chromosomes Sometimes there may be too many or too few This screen can also determine the sex of the baby

    Microdeletions In rare cases, a tiny piece of a chromosome is missing

    Normally cells contain 23 pairs of chromosomes

    Trisomy A trisomy occurs when the cells of the body contain an extra chromosome

    Trisomy 21 Down syndrome

    Trisomy 18 Edwards syndrome

    Trisomy 13 Patau syndrome

    4 5 6 7 8 9 10 11 12 1332

    16 17 18 19 20 21 22 X Y1514

    1

    CHROMOSOME CONDITIONS CAN HAVE VARYING OUTCOMES

    Screening overview Carrier screeningGenetic screening Noninvasive prenatal screening

  • • Typically cells contain 46 total chromosomes, organized into 23 pairs. One member of each pair comes from the mother, and the other comes from the father

    • Trisomic conditions occur when an individual has a total number of 47 chromosomes, instead of the typical 46. This excess genetic material can lead to specific conditions, depending on which chromosomal pair has an extra chromosome

    Trisomy 21: Down Syndrome • Individuals with Down syndrome have an extra copy of

    chromosome 21

    • People with Down syndrome typically have mild to moderate intellectual disability and may also have additional health conditions

    • Outcomes for people with Down syndrome have improved significantly in the past 40 years with increased access to education, social supports, employment opportunities, and family support

    • Down syndrome occurs in about 1 in 800 live births

    Trisomy 18: Edwards Syndrome • Individuals with Edwards syndrome have an extra copy of

    chromosome 18

    • Health problems in babies born with Edwards syndrome are usually life-threatening, including heart defects and breathing difficulties

    • Edwards syndrome occurs in about 1 in 5,000 live births. Miscarriages are common with affected pregnancies

    Trisomy 13: Patau Syndrome • Individuals with Patau syndrome have an extra copy of

    chromosome 13

    • Patau syndrome causes life-threatening birth defects and severe intellectual disability

    • Patau syndrome occurs in about 1 in 10,000 live births. Miscarriages are common with affected pregnancies

    Sex Chromosome Differences • The sex chromosomes determine whether the baby will be male

    (XY) or female (XX)

    • Sometimes there may be too many or too few sex chromosomes, resulting in potential health issues

    • In addition to assessing whether there are extra or missing sex chromosomes, noninvasive prenatal screening can also determi

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