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 disease that we will be learning about today is:

Trisomy X

Sometimes called triple X syndrome.

What is Trisomy X?

• Trisomy X is a chromosomal disorder that affects women in which they have an extra copy of the X chromosome, for a total of three copies instead of the typical two
• While believed to be somewhat common (potentially as frequent as 1 in 1,000 female births), the disorder is not often diagnosed.
  • This is primarily because some patients never experience any symptoms
• Trisomy X can be diagnosed prenatally or postnatally; generally, postnatally diagnosed cases are more severe because they are often recognized based on signs and symptoms.
• In most cases, people with the disorder can live normal lives; however, in a small minority, symptoms can be severe and debilitating
• Originally believed to be a severely disabling condition in practically all cases, trisomy X was first described by Patricia Jacobs, a geneticist, in 1959

How Do You Get It?

• Trisomy X occurs through a process called nondisjunction.
  • Sister chromatids or homologous chromosomes fail to separate during meiosis, the process that produces sperm cells and egg cells.
  • This results in cells with too few or too many chromosomes
  • Nondisjunction can also occur after conception
• In most cases, trisomy X is attributed to nondisjunction in the mother, during the production of eggs
• Older maternal age is a risk factor for nondisjunction
• Trisomy X otherwise tends to occur randomly, with little chance of recurrence or inheritance within a family

What Are The Symptoms?

• Many people with trisomy X do not have symptoms, and these patients are not often diagnosed as a result. However, symptoms can be serious when present. They can include:
  • Certain facial features, such as widely spaced eyes
  • Taller than average height, with growth being especially rapid between ages four and eight
  • Incurved little fingers
  • Hyper-extensible joints
  • Flat feet
  • Fusion of the forearm long bones
  • Early menopause
  • Increased risk of certain disorders and conditions, such as:
    • Sjögren’s syndrome
    • Lupus
    • Hip dysplasia
    • Sleep apnea
    • Scoliosis
    • Asthma
    • Kidney problems
    • Ovary malformation
    • Tremor
    • Autism
    • Mental health disorders
  • Slight delays in developmental milestones
  • Slightly lower than average IQ
    • In rare cases, more pronounced intellectual disability can occur

How Is It Treated?

• When mild symptoms are present, little treatment is necessary
• There is no cure for trisomy X; treatment is typically based on addressing symptoms or complications as they arise
• Periodic screenings or early interventions may be important if patients show signs of developmental delays or challenges
  • Examples include speech therapy, developmental therapy, or physical therapy
• Educational assistance may be needed if the child displays a learning disability
• Counseling and a supportive environment can also be critical for patients that display difficulties with mental health and mood
• Sometimes symptoms can impact daily function, and extra assistance and support may be required.

Where Can I Learn More???

• Check out our cornerstone on this disease here.
• Learn more about this condition from the National Organization for Rare Disorders.