Also known as Triple X;47,XXX
What is trisomy X syndrome?
Trisomy X syndrome, also known as triple X or 47,XXX, is a sex chromosome aneuploidy characterized by the presence of an extra X chromosome in females. Women and girls who have trisomy X may present with highly variable symptoms including tall stature (2-3" taller than expected for the family starting in adolescence), low muscle tone, and risks for neurodevelopmental disorders including developmental delays (especially speech-language delays), learning disabilities, ADHD, autism and anxiety. The presence and severity of symptoms widely vary between individuals, with some girls having few symptoms while others are more significantly affected. The onset of prenatal cell-free DNA screening has increased the identification of trisomy X in newborns and active research is being done to redefine the natural history of this condition when identified at birth.
Who gets trisomy X?
Trisomy X affects approximately 1 in 1,000 females, however many go undiagnosed their entire lives.
What causes trisomy X syndrome?
Trisomy X is caused by an extra X chromosome in girls, commonly due to the presence of an extra X chromosome in the egg or sperm at the time of conception due to nondisjunction (when the chromosomes do not divide properly) and is not typically inherited.
How is trisomy X syndrome diagnosed?
Trisomy X is a chromosome condition which can be diagnosed from blood tests. Tests that can diagnose trisomy X include a karyotype (chromosome analysis looking at the number and structure of chromosomes in cells), a chromosomal microarray (a more detailed chromosome study looking for deletions or duplications across all chromosomes) or genetic sequencing (reading through the DNA sequence carried on the chromosomes). Trisomy X may be suspected based on physical or neurodevelopmental differences during childhood and can be identified before birth by prenatal screening and/or diagnostic testing, such as an amniocentesis.
What is the treatment for trisomy X?
Treatments for trisomy X syndrome are specific to managing symptoms, which can be highly variable, and most commonly address medical, psychological and/or academic needs, when indicated. Since premature ovarian failure may be associated with trisomy X, hormone monitoring and fertility interventions may also be offered as treatments.
Frequently Asked Questions
Why did I get trisomy X syndrome?
Trisomy X is not caused by anything a person does or doesn't do, as it results from a biological process in which the chromosomes misdivide, called nondisjunction.
Will my trisomy X get worse?
The symptoms associated with trisomy X may or may not change overtime. Some symptoms, such as developmental delays or learning disabilities may be present from a very young age, whereas other symptoms, such as tall stature, may become more apparent later in childhood.
What things can I discuss with my primary care physician about trisomy X?
While there is no standard of care guidelines in trisomy X, talk with your doctor about your concerns or your child's struggles to ensure that appropriate referrals and evaluations are being pursued.