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What are Chromosome Abnormalities

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Most people have 23 pairs of chromosomes for a total of 46 — two copies of each pair. Panorama is highly effective in determining if there is an extra chromosome or if there is only one chromosome where there should be a pair. These are the chromosomal disorders that Panorama® is able to detect:

  • Trisomy 21 (Downs Syndrome)
    Babies with Down syndrome have three copies of chromosome 21 and have intellectual disabilities that range from mild to severe. Children with Down syndrome will need extra medical care depending on the child’s specific health problems. Early intervention has allowed many individuals with Down syndrome to lead healthy and productive lives. The presence of medical conditions, like heart defects, can affect the lifespan in these children and adults; however, most individuals with Down syndrome will live into their 60s. Miscarriage occurs in about 30% of pregnancies with Down syndrome while overall about 1 in 700 babies are born with Down syndrome.

  • Trisomy 18 (Edwards Syndrome)
    Babies with trisomy 18 have three copies of chromosome 18 and have severe intellectual disabilities and birth defects typically involving the heart, brain, and kidneys. Babies with trisomy 18 can also have visible birth defects such as an opening in the lip (cleft lip) with or without an opening in the roof of the mouth (cleft palate), small head, clubbed feet, underdeveloped fingers and toes, and a small jaw. Unfortunately, most pregnancies with trisomy 18 will miscarry. If born alive, most affected babies with trisomy 18 will pass away within the first few weeks of life. About 10 percent survive to their first birthday. Trisomy 18 occurs in approximately 1 in 3,000 live births.

  • Trisomy 13 (Patau Syndrome)
    Babies with trisomy 13 have three copies of chromosome 13 and have severe intellectual disabilities. They often have birth defect involving the heart, brain and kidneys. Visible abnormalities include extra fingers and or toes or an opening in the lip, with or without an opening in the palate. Given the severe disabilities, most pregnancies affected by trisomy 13 will miscarry.If born alive, most affected babies with trisomy 13 will pass away within the first few weeks of life. About 10 percent survive to their first birthday. Trisomy 13 occurs in approximately 1 in 5,000 live births.

  • Sex Chromosome Abnormalities
    These occur when there is an extra or missing copy of one of the sex chromosomes. One type of sex chromosome abnormality that affects girls is called Turner syndrome. Girls with Turner syndrome are missing one X chromosome. Other common sex chromosome abnormalities are caused by an extra chromosome. Although most affected individuals have an IQ that is in the normal range, some but not all, have learning disabilities or delays. In general, presentation is less severe than what is seen in trisomies 18, 13, and 21. Children with sex chromosomes abnormalities typically do not have major birth defects. The risk of some sex chromosome abnormalities increase with maternal age.

    • Monosomy X – Turner Syndrome
      Babies with monosomy X are females who have one X chromosome instead of two. Unfortunately, a high proportion of pregnancies with monosomy X will result in a miscarriage in the first or second trimester of pregnancy. Babies with monosomy X that make it to term may have heart defects, learning difficulties, and infertility. In most cases, girls with monosomy X will need extra medical care including hormone therapies at various stages of life.

  • Triploidy
    Panorama is currently the only NIPT that tests for triploidy. Babies with triploidy have a complete extra set of chromosomes for a total of 69 chromosomes instead of the usual 46. At 10 weeks gestation, one in 1,000 pregnancies is affected by triploidy. It is extremely rare for these pregnancies to reach term as they typically spontaneously miscarry early in pregnancy. Those few liveborns usually pass away within days of delivery due to heart, brain, and kidney problems. Babies with triploidy also often have birth defects affecting the extremities and face. Carrying a baby with triploidy can increase a mother's risk for a variety of conditions: pre-eclampsia (which can lead to seizures) and excessive bleeding after delivery. In rare instances, triploid pregnancies can persist and progress to a type of cancer called choriocarcinoma. Knowing about triploidy allows the physician to monitor the health of the mother appropriately.

  • Microdeletions
    Microdeletions are caused when a chromosome is missing a small piece. The severity of problems caused by a microdeletion is determined primarily by the size and location of the deletion. For instance, features of the 22q11.2 deletion syndrome tend to be different and may be less severe than Angelman syndrome, which is a microdeletion involving chromosome 15

    • 22q11.2 deletion syndrome
      The 22q11.2 deletion syndrome, also called DiGeorge syndrome or Velo-Cardio-Facial syndrome (VCFS), is caused by a missing piece of chromosome number 22. About one in every 2,000 babies is born with the 22q11.2 deletion syndrome. The majority of children with this disorder have heart defects, immune system problems, and specific facial features. Most children with 22q.11.2 deletion syndrome have mild-to-moderate intellectual disability and speech delays; some will also have low calcium levels, kidney problems, feeding problems and/or seizures. About one in five children with the 22q11.2 deletion syndrome have autism spectrum disorder; 1 in 4 adults with 22q11.2 deletion syndrome have a psychiatric illness, like schizophrenia.

    • Prader-Willi syndrome
      Prader-Willi syndrome occurs when either a small piece of chromosome 15 is missing or when both copies of chromosome 15 come from the same parent (called uniparental disomy, or UPD). Babies with Prader-Willi syndrome have low muscle tone and problems with growth and feeding. Children with Prader-Willi syndrome have delayed milestones, short stature, rapid weight gain leading to obesity, and intellectual disability. About 1 in 10,000 babies are born with Prader-Willi syndrome.

    • Angelman syndrome
      Angelman syndrome happens when either a small piece of chromosome 15 is missing, or when both copies of chromosome 15 come from the same parent (called uniparental disomy, or UPD). About 1 in 12,000 babies are born with Angelman syndrome. Babies and children with Angelman syndrome have severe intellectual disability, delayed milestones, seizures, and problems with balance and walking.

    • 1p36 deletion syndrome
      1p36 deletion syndrome, also referred to as Monosomy 1p36 syndrome, is caused by a missing piece of chromosome 1. Children with 1p36 deletion syndrome have intellectual disabilities. Most have heart defects and weak muscle tone. About half of affected individuals have seizures (epilepsy), behavioral problems and hearing loss. Some children with 1p36 deletion syndrome also have vision problems or additional birth defects of other organs. About 1 in 5,000 newborn babies has 1p36 deletion syndrome.

    • Cri-du-chat syndrome
      A missing piece of chromosome 5 causes Cri-du-chat syndrome, also called 5p- (5p minus) syndrome. The name “Cri-du-chat” was given to this syndrome due to the high-pitched, cat-like cry that babies with this syndrome often make. Babies with Cri-du-chat syndrome typically have low birth weight, a small head size and weak muscle tone. Feeding and breathing problems are common in infancy. Children with this disorder have moderate-to-severe intellectual disability, including speech and language delays. They may also have growth delays, behavior problems, and some have curvature of the spine (scoliosis). About one in every 20,000 babies is born with Cri-du-chat syndrome. They may also have heart defects, growth delay, behavior problems and some have curvature of the spine.

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