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 problems 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, which vary among individuals. These signs and symptoms may show up as:

• Delayed development of speech and language skills, as well as motor skills, such as sitting up and walking
• Learning disabilities, such as difficulty with reading, understanding or math
• Behavioral problems, such as attention-deficit/hyperactivity disorder (ADHD) or symptoms of autism spectrum disorder
• Psychological problems, such as anxiety and depression
• Problems with fine and gross motor skills, memory, judgment and information processing

Sometimes females with triple X syndrome have these signs and symptoms:

• Vertical folds of skin that cover the inner corners of the eyes (epicanthal folds)
• Widely spaced eyes
• Curved pinky fingers
• Flat feet
• Breastbone with an inward bowed shape
• Weak muscle tone (hypotonia)
• Seizures
• Problems with the kidneys
• Ovaries that don’t work properly at a young age (premature ovarian failure)

If you’re concerned about any signs or symptoms, make an appointment to talk with your family health care provider or pediatrician, who can help determine the cause and suggest appropriate action.