Klinefelter syndrome (KS) is a condition that occurs in men who have an extra X chromosome. The syndrome can affect different stages of physical, language, and social development.
The most common symptom is infertility. Boys may be taller than other boys their age, with more fat around the belly. After puberty, KS boys may have
Smaller testes and penis
Breast growth
Less facial and body hair
Reduced muscle tone
Narrower shoulders and wider hips
Weaker bones
Decreased sexual interest
Lower energy
KS males may have learning or language problems. They may be quiet and shy and have trouble fitting in.
A genetic test can diagnose KS. There is no cure, but treatments are available. It is important to start treatment as early as possible. With treatment, most boys grow up to have normal lives.
Treatments include testosterone replacement therapy and breast reduction surgery. If needed, physical, speech, language, and occupational therapy may also help.
NIH: National Institute of Child Health and Human Development
