What Is XYY Syndrome?
Often undiagnosed, XYY syndrome only affects males.
XYY syndrome (also called Jacobs syndrome, XYY karyotype, or YY syndrome) is a rare chromosomal birth defect that occurs when a male infant is born with an extra Y chromosome.
Instead of having one X and one Y sex chromosome, those with XYY syndrome have one X and two Y chromosomes.
Sex chromosome abnormalities like XYY syndrome are some of the most common chromosome abnormalities.
XYY syndrome affects only males, and according to the National Institutes of Health (NIH), the condition occurs in about 1 in 1,000 live births, with 5 to 10 boys with XYY syndrome born daily in the United States.
Causes of XYY Syndrome
Most cases of XYY syndrome are not inherited, and the syndrome occurs randomly in pregnancies of women from all ages and ethnic backgrounds.
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 normally have two X chromosomes, while males have one X chromosome and one Y chromosome.
However, boys born with XYY syndrome have an extra Y chromosome in each cell of their body.
Most of these cases are due to a cell-division error in the sperm prior to conception known as nondisjunction.
The exact reason why this nondisjunction error occurs is not known.
Features of XYY Syndrome
Newborns with XYY syndrome dont display noticeable physical characteristics.
The most common physical trait is being tall, which is usually obvious after five or six years of age, and results in an average adult height of 6 feet, 3 inches.
While characteristics vary widely among boys and men with XYY syndrome, other features may include the following:
- Comparatively low weight relative to stature
- Larger head dimensions
- Severe acne in adolescence
- Behavior and emotional difficulties
- Learning disabilities and delayed development of speech and language skills
- Delayed development of motor skills, such as sitting and walking
- Weak muscle tone (hypotonia), hand tremors, or other involuntary movements (motor tics)
- Slightly lower IQ than normal
- Diagnosis of autistic spectrum disorders occurs in a small percentage of those with XYY syndrome
There is not an increased risk of diseases in childhood or adulthood for people with XYY syndrome.
Those with the syndrome experience puberty at expected times, as well as normal development of sex organs and of secondary sex characteristics.
While those with XYY syndrome may have decreased sperm quality with immature sperm cells, they are still fertile.
Additionally, its very rare for men with XYY syndrome to conceive sons with the same syndrome.
Diagnosis of XYY Syndrome
Since there is often times no medical reason to test for XYY syndrome, the diagnosis is commonly never made.
In fact, Kaiser Permanente reports that 88 percent of males with XYY syndrome are never diagnosed because there are few or no problematic symptoms.
With that said, a diagnosis can be made before birth while a baby is still in the mothers womb. According to Kaiser Permanente, about 5 percent of boys with XYY are identified through prenatal testing.
XYY syndrome is generally diagnosed when prenatal karyotyping is done for the detection of Down syndrome and other major conditions.
This is detected with amniocentesis, which involves gathering a sample of fluid that surrounds the fetus or through chorionic villus sampling (CVS), the removal of tissue samples from a portion of the placenta.
Both samples can reveal if an extra Y chromosome is present.
If prenatal diagnosis is not done, a small percentage of boys may be diagnosed because of learning problems, developmental delay, or behavior issues.
A blood test can also accurately diagnose XYY syndrome.
Treatment of XYY Syndrome
Since its impossible to correct every sex chromosome in our bodies, there is no treatment for XYY syndrome.
However, a person with XYY syndrome can get help with any learning or developmental delays through speech therapy, occupational therapy, or other assistance.
Attention deficit and hyperactivity disorder (ADHD), difficulties with social interactions, and other behavioral problems can be treated with therapy or medication, just like they would for anyone facing these challenges.
In most cases, people with XYY syndrome respond well to intervention and treatment, and many issues improve within a few years.
Sources:
- XYY Syndrome; Kaiser Permanente.
- XYY Syndrome; National Organization for Rare Disorders.
- XYY Syndrome; University of California DDHealthInfo.org.
- 47, XYY syndrome; National Institutes of Health.
Source: http://www.everydayhealth.com
