Rare Classroom: Trisomy 18

Welcome to the Rare Classroom, a new series from Patient Worthy. Rare Classroom is designed for the curious reader who wants to get informed on some of the rarest, most mysterious diseases and conditions. There are thousands of rare diseases out there, but only a very small number of them have viable treatments and regularly make the news. This series is an opportunity to learn the basics about some of the diseases that almost no one hears much about or that we otherwise haven’t been able to report on very often.

Eyes front and ears open. Class is now in session.

The rare disease that we will be learning about today is:

Trisomy 18

Also commonly referred to as Edwards Syndrome.

What is Trisomy 18?

  • Trisomy 18, or Edwards syndrome, is a genetic disorder caused by the appearance of a third copy of all or part of chromosome 18
  • This disorder often leads to severe effects impacting vital parts of the body
  • Mosaic trisomy 18 can also occur, in which not all cells have the extra chromosome copy. This results in less serious symptoms
  • The vast majority of pregnancies impacted by trisomy 18 do not result in live birth, and in many of those that do, the infant does not survive for long
  • The disorder was first recognized by John Hilton Edwards, in 1960
  • Trisomy 18 occurs in about 1 in every 5,000 births

How Do You Get It?

  • This disease is a chromosomal disorder in which an extra, third copy of genetic information occurs on chromosome 18
  • Females seem to be affected more often and are also more often to survive to birth
  • It’s pretty rare for Trisomy 18 to be passed down from parents
    • Instead, the illness appears as a result of issues that occur either during early development or during the creation of the reproductive cells
  • The risk of having a child with this disease increases as the mother’s age increases

What Are The Symptoms?

  • Symptoms of Trisomy 18 include:
    • Small birth weight
    • Heart defects
      • Patent ductus arteriosus, Atrial septal defect, Ventricular septal defect
    • Severe intellectual disability
    • Small jaw
    • Clenched fists
    • Overlapping fingers
    • Kidney malformations
    • Esophageal atresia
    • Upturned nose
    • Cleft palate
    • Intestines protruding from the body
    • Feeding difficulties
    • Grow problems
    • Joint contractures
    • Breathing issues
    • Widely spaced eyes
    • Narrow eyelids
    • Webbed toes
    • Clubbed feet or rocker bottom feet
    • Undescended testicles
    • Underdeveloped thumbs and nails
  • Cardiac and central nervous system abnormalities are the most commonly identified signs in utero

How Is It Treated?

  • Treatment options for Trisomy 18 are very limited, and are generally supportive in nature. Examples include:
    • Surgery to correct heart defects
    • Orthopedic interventions, such as bracing or surgery
    • Feeding assistance, such as feeding tubes
  • Unfortunately, the defects and symptoms of the disorder are severe, and at best, only around 10 percent of children born with trisomy 18 survive for more than a year

Where Can I Learn More???

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