Triple X syndrome, also called trisomy X or 47,XXX, is a genetic disorder that affects about 1 in 1,000 females. Females normally have two X chromosomes in all cells — one X chromosome from each parent. In triple X syndrome, a female has three X chromosomes.
Many girls and women with triple X syndrome don't experience symptoms or have only mild symptoms. In others, symptoms may be more apparent — possibly including developmental delays and learning disabilities. Seizures and kidney abnormalities occur in a small number of girls and women with triple X syndrome.
Treatment for triple X syndrome depends on which symptoms, if any, are present and their severity.
Signs and symptoms can vary greatly among girls and women with triple X syndrome. Many experience no noticeable effects or have only mild symptoms.
Being taller than average height is the most typical physical feature. Most females with triple X syndrome experience normal sexual development and have the ability to become pregnant. Some girls and women with triple X syndrome have intelligence in the normal range, but possibly slightly lower when compared with siblings. Others may have intellectual disabilities and sometimes may have behavioral problems.
Occasionally significant symptoms may occur. If signs and symptoms are present, they are often variable. Signs and symptoms in girls and women with triple X syndrome may include an increased risk of:
Sometimes triple X syndrome may be associated with these signs and symptoms:
If you're concerned about your child's development, make an appointment to talk with your family doctor or pediatrician. Your doctor can help determine the cause and suggest appropriate action.
Although triple X syndrome is genetic, it's usually not inherited — it's due to a random genetic error.
Normally, people have 46 chromosomes in each cell, organized into 23 pairs, including two sex chromosomes. One set of chromosomes is from the mother and the other set is from the father. These chromosomes contain genes, which carry instructions that determine everything from height to eye color.
The pair of sex chromosomes — either XX or XY — determines a child's sex. A mother can give the child only an X chromosome, but a father can pass on an X or a Y chromosome:
Females with triple X syndrome have a third X chromosome from a random error in cell division. This error can happen before conception or early in the embryo's development, resulting in one of these forms of triple X syndrome:
Triple X syndrome is also called 47,XXX syndrome because the extra X chromosome results in 47 chromosomes in each cell instead of the usual 46.
Although some females may have mild or no symptoms associated with triple X syndrome, other girls and women experience developmental, psychological and behavioral problems that may lead to a variety of other issues, including:
Because many girls and women with triple X syndrome are healthy and show no outward signs of the condition, they may remain undiagnosed all their lives, or the diagnosis may be discovered while checking other issues. Triple X syndrome may also be discovered during prenatal testing to identify other genetic disorders.
If triple X syndrome is suspected based on signs and symptoms, it can be confirmed by genetic testing — chromosome analysis using a blood sample. In addition to genetic testing, genetic counseling can help you gain comprehensive information about triple X syndrome.
The chromosome error that causes triple X syndrome can't be repaired, so the syndrome itself has no cure. Treatment is based on symptoms and needs. Options that may be helpful include:
It's quite possible for girls and women with triple X syndrome to lead full and happy lives. However, sometimes help and support are needed. Both you and your child may benefit from these strategies:
Here's some information to help you get ready for your appointment, and what you might expect from your doctor. You may want to bring a family member or friend to the appointment for support and to help you remember information.
Before your appointment, make a list of:
Some basic questions to ask the doctor include:
Don't hesitate to ask any other questions during your appointment.
Your doctor is likely to ask you a number of questions. Be ready to answer them to reserve time to go over points you want to focus on. Your doctor may ask:
Your doctor or mental health professional will ask additional questions based on responses, symptoms and needs. Preparing and anticipating questions will help you make the most of your time with the doctor.