Trisomy X affects approximately 1 in 1,000 females. Girls and women with 47,XXX can be completely symptom-free and unaware of their extra X chromosome, or they can have significant developmental, medical, and psychological issues.
As you can see in the adjoining photo collage of girls and young women with 47,XXX, the condition is not characterized by any prominent physical features. Affected children and adults do not look any different than their peers, though they may be somewhat taller and demonstrate subtle physical attributes including a curved little finger, epicanthal eyelid fold (skin curving slightly down toward the inner eye), and flat feet.
47,XXX may produce the following additional symptoms, although most affected individuals will have only some of them:
- Low muscle tone
- Speech delay/expressive language disorder
- Genito-urinary or kidney malformations
- Primary ovarian failure
- Subtle developmental delays
- Learning disability
- Attention deficits
Because symptoms are subtle and vary widely from one person to the next, only 30 percent of affected individuals are diagnosed during their lifetimes. Some may be identified prenatally due to maternal testing (amniocentesis, CVS, or non-invasive cell free DNA blood test) for advanced maternal age or other risk factors.
Another point at which 47,XXX may be detected is during infertility testing in adulthood or during non-invasive prenatal testing when the mother’s extra X may be detected during cell-free DNA blood work.
The Case for Testing
One of the goals of AXYS is to encourage families to be aware of the developmental, medical and psychosocial issues that may accompany 47,XXX. Cases involving a history of symptoms such as speech delay, learning disability, developmental problems or genito-urinary malformations should be followed up with genetic testing to determine if the cause is an X and Y variation.
Testing for 47,XXX involves a specialized blood test, either a karyotyping or a microarray. Health care professionals, including physicians, may be unfamiliar with the cognitive, developmental and medical conditions associated with 47,XXX. They often associate genetic syndromes with dysmorphia (characteristic facial or body features) or with intellectual disability, and fail to suggest genetic testing.
Frequently Asked Questions about 47,XXX (Scroll to relevant section partway down the page.)
Thanks to the generosity of the book’s author, Virginia Isaac’s Cover, MSW, AXYS is pleased to make this book available to the X and Y variation community, in its entirety, at no cost. Please feel free to download and/or print it for your personal use. (Those wishing to purchase a soft-bound copy can do so at Amazon or Kindle. All proceeds from the sale of this book benefit AXYS.)
For Children and Adolescents
Talking to your daughter: “My Guide to Trisomy X”
Other Trisomy X Websites
Contactgroep Triple-X Syndroom (The Netherlands)