XYY syndrome is a genetic
condition found in males only. About 1 in 1,000 boys have it.
Boys with XYY syndrome — also known as 47,XYY — might be taller than
other boys. Other symptoms can include problems with spoken language and processing
spoken words, coordination problems, weaker muscles, hand tremors, and behavioral
Most boys with XYY syndrome can grow up healthy, have normal sexual
development and fertility, and lead productive lives.
Symptoms can vary greatly among boys. Depending on which symptoms a boy has and
how severe they are, doctors may recommend various treatments.
What Causes XYY Syndrome?
Boys who have XYY syndrome are born with it. It's called XYY because they have
an extra Y chromosome in most or all of their cells.
Usually, a person has 46 chromosomes in each cell, divided into 23 pairs, which
includes two sex chromosomes. Half of the chromosomes are inherited from the father
and the other half from the mother. The chromosomes contain genes, which determine
an individual's characteristics, such as eye color and height. Boys typically have
one X chromosome and one Y chromosome, or XY, but boys with XYY syndrome have an extra
Y chromosome, or XYY.
XYY syndrome is not caused by anything the parents did or did not do. The disorder
is a random error in cell division. This error can happen before conception in the
reproductive cells of the mother or the father, or early in the embryo's development.
When the extra chromosome is the result of incorrect cell division early in the
embryo's development, a boy may have a mosaic form of XYY syndrome.
This means some of the cells have an extra Y chromosome, but not all do. Boys with
mosaic XYY syndrome usually have fewer symptoms.
What Are the Signs & Symptoms of XYY Syndrome?
Noticeable signs and symptoms of XYY syndrome can vary greatly. Some boys have
no obvious signs, while others have mild symptoms. Occasionally, the disorder causes
Boys with XYY syndrome may have some or all of these physical symptoms to some
taller than average height
low muscle tone, or muscle weakness (called hypotonia)
very curved pinky finger (called clinodactyly)
widely spaced eyes (called hypertelorism)
cystic acne during adolescence
Some boys also may have delayed development of their social, language, and learning
skills. They also can have problems with reading and understanding math, and may have
mild delays with coordination.
What Problems Can Happen?
Some boys with XYY syndrome may develop behavioral problems, such as ADHD,
autism, explosive temper, impulsivity, or defiant behavior. These problems might ease
as they get older and reach adulthood. Otherwise, treatment can help manage them.
A small number of boys may have increased testicular size for their age, or have
an increased risk for asthma
How Is XYY Syndrome Diagnosed?
Many boys with XYY syndrome are healthy and have no obvious symptoms. So sometimes
the condition isn't diagnosed or is only found while a doctor checks for a different
XYY syndrome often is found because parents talked with a doctor about concerns
with their son's development. This can help boys receive a diagnosis early. Research
has shown that early interventions and treatments are more effective.
To diagnosis XYY syndrome, a blood sample is checked for the presence of the extra
Y chromosome. Before birth, the condition can be found through a chromosomal
analysis. Testing is done on the fluid surrounding the fetus, tissue from the placenta,
or the blood from the mother.
How Is XYY Syndrome Treated?
There's no cure for XYY syndrome, but there are treatment options that can help
address specific symptoms.
Finding services early is important and can greatly increase their ability to help
your son live a healthier, more productive life. Options vary greatly depending on
how old a boy is at the time of his diagnosis, whether he has noticeable symptoms,
and the severity of those symptoms.
Treatments can include:
Regular doctor visits. At periodic visits, a doctor can monitor
a boy's development for delays, social and language disabilities, or health problems
and treat these promptly.
Early intervention services. It can be very helpful and often
more effective for a boy to have speech,
physical, or developmental
therapy in the early months of life or as soon as concerns are identified.
Speech therapy and physical therapy can improve your son's speaking, reading, and
writing skills and help increase strength and coordination. Occupational therapy and
behavioral therapy can help your son develop more confidence and interact better with
Counseling. The whole family can benefit from counseling to better
understand XYY syndrome and help a boy who has it to live a productive life.
Early inventions should be considered at infancy for physical therapy, at 15 months
for speech delay, at 1st grade for reading and learning issues, and at 3rd grade for
anxiety or depression.
Boys with XYY syndrome can develop speech, learning, or social challenges at a
young age. This can make them more likely to have low self-esteem
and lead to school or social problems.
If your son is having trouble making friends or struggles in school, talk to your
doctor or the principal or school counselor. Counseling and therapy can teach your
son practical skills to help him make friends and feel more confident in school, and
educational services can help your son succeed academically.
It's important to speak to your doctor if you have any concerns about your son's
physical and emotional development.