- Home
- Parents Home
- Allergy Center
- Asthma Center
- Cancer Center
- Diabetes Center
- A to Z Dictionary
- Emotions & Behavior
- First Aid & Safety
- Food Allergy Center
- General Health
- Growth & Development
- Flu Center
- Heart Health
- Homework Help Center
- Infections
- Diseases & Conditions
- Nutrition & Fitness Center
- Play & Learn Center
- School & Family Life
- Pregnancy Center
- Newborn Center
- Q&A
- Recipes
- Sports Medicine Center
- Doctors & Hospitals
- Videos
- Para Padres
- Home
- Kids Home
- Asthma Center
- Cancer Center
- Movies & More
- Diabetes Center
- Getting Help
- Feelings
- Puberty & Growing Up
- Health Problems of Grown-Ups
- Health Problems
- Homework Center
- How the Body Works
- Illnesses & Injuries
- Nutrition & Fitness Center
- Recipes & Cooking
- Staying Healthy
- Stay Safe Center
- Relax & Unwind Center
- Q&A
- Heart Center
- Videos
- Staying Safe
- Kids' Medical Dictionary
- Para Niños
- Home
- Teens Home
- Asthma Center
- Be Your Best Self Center
- Cancer Center
- Diabetes Center
- Diseases & Conditions
- Drugs & Alcohol
- Expert Answers (Q&A)
- Flu Center
- Homework Help Center
- Infections
- Managing Your Medical Care
- Managing Your Weight
- Nutrition & Fitness Center
- Recipes
- Safety & First Aid
- School & Work
- Sexual Health
- Sports Center
- Stress & Coping Center
- Videos
- Your Body
- Your Mind
- Para Adolescentes
A to Z: XXY Syndrome
May also be called:Klinefelter Syndrome; XXY Condition
XXY syndrome, also called Klinefelter syndrome, is a fairly common genetic condition. It happens when a boy is born with an extra sex chromosome in most or all of his cells.
More to Know
Genetic material, or DNA, is contained in tiny structures called chromosomes found inside the body's cells. A person's biological sex is determined by the sex chromosomes: females have two X chromosomes, or XX; most males have one X chromosome and one Y chromosome, or XY. Males with XXY syndrome are born with cells that have an extra X chromosome, or XXY. This can cause delayed development and puberty, a smaller penis and testicles, infertility, and other symptoms.
The condition that causes XXY syndrome is present at birth and can't be changed. But educational treatments and various types of therapy (physical therapy, speech therapy, behavioral and mental health counseling, and occupational therapy) can help someone keep pace in school and overcome problems with shyness and social development.
Keep in Mind
Kids and teens with XXY syndrome sometimes have trouble fitting in with kids their own age. With early help, in adulthood most will have normal social relationships with friends, family members, coworkers, and others.
All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.
Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.
© 1995- The Nemours Foundation. KidsHealth® is a registered trademark of The Nemours Foundation. All rights reserved.
Images sourced by The Nemours Foundation and Getty Images.