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47 XXX syndrome

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Alternate names

Trisomy X; Triple X syndrome; Triple-X female; XXX syndrome; Triple-X chromosome syndrome; Triplo X syndrome

Definition

47 XXX syndrome, also called trisomy X or triple X syndrome, is characterized by the presence of an additional (third) X chromosome in each of a female's cells (which normally have two X chromosomes). Although females with this condition may be taller than average, this chromosomal change typically causes no unusual physical features. Most females with triple X syndrome have normal sexual development and are able to conceive children.

XXX syndrome (female).svg
XXX syndrome (male).svg

Epidemiology

This condition occurs in about 1 in 1,000 newborn girls. Five to 10 girls with triple X syndrome are born in the United States each day.

Cause

  • People normally have 46 chromosomes in each cell. Two of the 46 chromosomes, known as X and Y, are called sex chromosomes because they help determine whether a person will develop male or female sex characteristics.
  • Females typically have two X chromosomes (46,XX), and males have one X chromosome and one Y chromosome (46,XY).
  • Triple X syndrome results from an extra copy of the X chromosome in each of a female's cells.
  • As a result of the extra X chromosome, each cell has a total of 47 chromosomes (47,XXX) instead of the usual 46.
  • An extra copy of the X chromosome is associated with tall stature, learning problems, and other features in some girls and women.
  • Some females with triple X syndrome have an extra X chromosome in only some of their cells.
  • This phenomenon is called 46,XX/47,XXX mosaicism.

Inheritance

  • Most cases of triple X syndrome are not inherited.
  • The chromosomal change usually occurs as a random event during the formation of reproductive cells (eggs and sperm).
  • An error in cell division called nondisjunction can result in reproductive cells with an abnormal number of chromosomes.
  • For example, an egg or sperm cell may gain an extra copy of the X chromosome as a result of nondisjunction.
  • If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra X chromosome in each of the body's cells.
  • 46,XX/47,XXX mosaicism is also not inherited.
  • It occurs as a random event during cell division in early embryonic development.
  • As a result, some of an affected person's cells have two X chromosomes (46,XX), and other cells have three X chromosomes (47,XXX).

Signs and symptoms

  • Many women with 47 XXX syndrome have no symptoms or only mild symptoms.
  • In other cases, symptoms may be more pronounced.
  • Females with 47 XXX syndrome may be taller than average, but the condition usually does not cause unusual physical features.
  • Minor physical findings can be present in some individuals and may include epicanthal folds, hypertelorism (widely spaced eyes), upslanting palpebral fissures, clinodactyly, overlapping digits (fingers or toes), pes planus (flat foot), and pectus excavatum.
  • The condition is associated with an increased risk of learning disabilities and delayed development of speech and language skills.
  • Delayed development of motor skills (such as sitting and walking), weak muscle tone (hypotonia), and behavioral and emotional difficulties are also possible, but these characteristics vary widely among affected girls and women.
  • Seizures or kidney abnormalities occur in about 10 percent of affected females.
  • Most females with the condition have normal sexual development and are able to conceive children.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

30%-79% of people have these symptoms

  • Clinodactyly of the 5th finger(Permanent curving of the pinkie finger)
  • Cognitive impairment(Abnormality of cognition)
  • Epicanthus(Eye folds)
  • Global developmental delay
  • Muscular hypotonia(Low or weak muscle tone)
  • Specific learning disability
  • Tall stature(Increased body height)

5%-29% of people have these symptoms

Diagnosis

  • 47 XXX syndrome may first be suspected based on the presence of certain developmental, behavioral or learning disabilities in an individual. T
  • he diagnosis can be confirmed with chromosomal analysis (karyotyping), which can be performed on a blood sample.
  • This test would reveal the presence of an extra X chromosome in body cells.
  • 47 XXX syndrome may also be identified before birth (prenatally), based on chromosomal analysis performed on a sample taken during an amniocentesis or by a chorionic villus sampling (CVS) procedure.
  • However, in these cases, confirmation testing with a test called FISH, which gives more details of the chromosomes, is recommended in order to evaluate the fetus for mosaicism (when only some of the cells have the extra X chromosome).

Treatment

  • There is no cure for 47 XXX syndrome, and there is no way to remove the extra X chromosome that is present in an affected individual's cells.
  • Management of the condition varies and depends on several factors including the age at diagnosis, the specific symptoms that are present, and the overall severity of the disorder in the affected individual.

Recommendations include:

Early intervention services for infants and children that are diagnosed with the condition

  • Evidence suggests that children with 47 XXX syndrome are very responsive to early intervention services and treatment. These services may include speech, occupational, physical or developmental therapy, starting in the early months of life or as soon as needs are identified.

Periodic screenings throughout childhood

  • Specific recommendations include developmental assessment by 4 months of age to evaluate muscle tone and strength; language and speech assessment by 12 months of age; pre-reading assessment during preschool years; and an assessment of additional learning disabilities as well as social and emotional problems.

Educational assistance

  • Receiving educational help to learn techniques and strategies to be successful in school and daily life.

Supportive environment and counseling

  • Girls with triple X syndrome may be more prone to anxiety, as well as behavior and emotional problems. It is important to have a supportive environment and psychological counseling which may help teaching the family how to demonstrate love and encouragement, and discourage behaviors that might negatively impact learning and social functioning.

Assistance and support in daily functioning

  • If there is developmental delays, this assistance and support may include help with activities of daily living, social opportunities and employment.

It is also recommended that infants and children with 47 XXX syndrome receive kidney and heart evaluations to detect possible abnormalities. Adolescent and adult women who have late periods, menstrual abnormalities, or fertility issues should be evaluated for primary ovarian failure (POF). Additional treatment for this disorder depends on the specific signs and symptoms present in the affected individual.

NIH genetic and rare disease info

47 XXX syndrome is a rare disease.

Latest research - 47 XXX syndrome

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