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XXY Chromosomes (XXY Males (Klinefelter Syndrome))

What is Klinefelter syndrome (XXY Chromosomes)?

Klinefelter syndrome is a chromosomal condition that affects male physical and cognitive development.
Klinefelter syndrome is a genetic condition that results when a boy is born with an extra copy of the X chromosome. Klinefelter syndrome is a common genetic condition affecting males, and it often isn't diagnosed until adulthood.
Chromosomes are packages of genes found in every cell in the body. Two types of chromosome, called the sex chromosomes, determine the genetic sex of a baby. These are named either X or Y.
Usually, a female baby has two X chromosomes (XX) and a male has one X and one Y (XY). But in Klinefelter syndrome, a boy is born with an extra copy of the X chromosome (XXY).
The X chromosome is not a "female" chromosome and is present in everyone. The presence of a Y chromosome denotes male sex.
Boys and men with Klinefelter syndrome are still genetically male, and often will not realise they have this extra chromosome, but occasionally it can cause problems that may require treatment.
Klinefelter syndrome is quite common, affecting around 1 in every 660 males.

What are symptoms of XXY Chromosomes?

Not all males with the condition have the same symptoms or to the same degree. Symptoms depend on how many XXY cells a man has, how much testosterone is in his body, and his age when the condition is diagnosed. The XXY condition can affect three main areas of development 1) physical, 2) language, and 3) social.
Signs and symptoms of Klinefelter syndrome vary widely among males with the disorder. Many boys with Klinefelter syndrome have few noticeable signs, and the condition may go undiagnosed until adulthood. For others, the condition has a noticeable effect on growth or appearance.

Signs and symptoms of Klinefelter syndrome also vary by age.


Signs and symptoms may include:

Weak muscles
Slow motor development — taking longer than average to sit up, crawl and walk
Delay in speaking
Quiet, docile personality
Problems at birth, such as testicles that haven't descended into the scrotum

Boys and teenagers

Signs and symptoms may include:

Taller than average stature
Longer legs, shorter torso and broader hips compared with other boys
Absent, delayed or incomplete puberty
After puberty, less muscle and less facial and body hair compared with other teens
Small, firm testicles
Small penis
Enlarged breast tissue (gynecomastia)
Weak bones
Low energy levels
Tendency to be shy and sensitive
Difficulty expressing thoughts and feelings or socializing
Problems with reading, writing, spelling or math


Low sperm count or no sperm
Small testicles and penis
Low sex drive
Taller than average height
Weak bones
Decreased facial and body hair
Less muscular than normal
Enlarged breast tissue
Increased belly fat

How is Klinefelter syndrome diagnosed?

Klinefelter syndrome isn't necessarily anything serious, but treatment can help reduce some of the symptoms if necessary.
In many cases, it's only detected if a man with the condition undergoes fertility tests.
Your doctor will likely do a thorough physical exam and ask detailed questions about symptoms and health. This may include examining the genital area and chest, performing tests to check reflexes, and assessing development and functioning.

The main tests used to diagnose Klinefelter syndrome are:

Hormone testing. Blood or urine samples can reveal abnormal hormone levels that are a sign of Klinefelter syndrome.
Chromosome analysis. Also called karyotype analysis, this test is used to confirm a diagnosis of Klinefelter syndrome. A blood sample is sent to the lab to check the shape and number of chromosomes.
A small percentage of males with Klinefelter syndrome are diagnosed before birth. This might be identified after a pregnant woman has a procedure to examine fetal cells drawn from the amniotic fluid (amniocentesis) or placenta for another reason, such as being older than age 35 or having a family history of genetic conditions.

What are the treatments for the Klinefelter syndrome?

If you or your son is diagnosed with Klinefelter syndrome, your health care team may include a doctor who specializes in diagnosing and treating disorders involving the body's glands and hormones (endocrinologist), a speech therapist, a pediatrician, a physical therapist, a genetic counselor, a reproductive medicine or infertility specialist, and a counselor or psychologist.
The XXY chromosome pattern can not be changed. But, there are a variety of ways to treat the symptoms of the XXY condition.

Educational treatments - As children, many XXY males qualify for special services to help them in school. Teachers can also help by using certain methods in the classroom, such as breaking bigger tasks into small steps.
Therapeutic options - A variety of therapists, such as physical, speech, occupational, behavioral, mental health, and family therapists, can often help reduce or eliminate some of the symptoms of the XXY condition, such as poor muscle tone, speech or language problems, or low self-confidence.
Medical treatments - Testosterone replacement therapy (TRT) can greatly help XXY males get their testosterone levels intonormal range. Having a more normal testosterone level can help develop bigger muscles, deepen the voice, and grow facial and body hair. TRT often starts when a boy reaches puberty. Some XXY males can also benefit fromfertility treatment to help them father children.

One of the most important factors for all types of treatment is starting it as early in life as possible.

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