Klinefelter Syndrome


Checking to see if a newborn boy has an extra X chromosome is not a normal post-birth test, although perhaps it should be. The resulting condition – known as Klinefelter Syndrome – is a common enough genetic condition that often is not diagnosed until the baby boy has grown into a man.

Klinefelter syndrome is not inherited and cannot be predicted: It is the result of a genetic roll of the dice. The most common cause is an extra X chromosome in each cell. A less severe form of the condition – called mosaic Klinefelter syndrome – is caused by an extra X chromosome in just some cells.

Not every man with Klinefelter syndrome will display the same symptoms, but they usually find themselves making a doctor's appointment when they notice their testicles and/or penis are smaller than normal or they have enlarged breast tissue. Other symptoms may include:

  • Low sperm count or no sperm
  • Low sex drive
  • Taller than average height
  • Weak bones
  • Decreased facial and body hair
  • Less muscular than normal
  • Increased belly fat

Symptoms to be on the lookout for in babies 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

Klinefelter syndrome symptoms when diagnosed in boys and teenagers 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
  • 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

Your doctor can diagnose Klinefelter syndrome via a chromosome analysis which is effected through a blood test.

There is no fixing an extra chromosome. Treatment of Klinefelter syndrome breaks down to treating its myriad symptoms, and so will often involve a team of specialists. These may include a physical therapist, endocrinologist, speech therapist, genetic counselor,  infertility specialist and a psychologist.

Tools and techniques employed by these doctors may include testosterone replacement therapy, surgical removal of breast tissue, physical therapy to compensate for muscle weakness and intracytoplasmic sperm injection to facilitate fathering a child.


Sources: The Mayo Clinic