Klinefelter Syndrome

is a disorder of the human sex chromosomes that occurs in males. That Affect male physical and perceptional development. Klinefelter syndrome is one of the most frequent chromosomal disorders in males, occurring in approximately 1 in every 500 to 1,000 males. It results from an unequal sharing of sex chromosomes very soon after fertilization, with one cell of a dividing pair receiving two X chromosomes and a Y chromosome and the other cell of the pair receiving only a Y chromosome and usually dying. (The normal male chromosome number and sex chromosome composition are 46, XY.)


Klinefelter Syndrome is named for Harry Klinefelter, an American physician who described this disorder, in 1942. He also described its set of Symptoms that characterized the Physical and Perceptional conditions.

The Syndrome was first identified by British researcher Patricia A. Jacobs and her colleagues with a specific Chromosomal abnormality in 1959.

Signs & Symptoms


Signs and Symptoms of Klinefelter Syndrome vary by Age


  • 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.

Boyes & Teenagers

  • Taller than average stature.
  • Longer legs, shorter torso and broader hips compared with other boys.
  • Absent, delayed or incomplete puberty.
  • After puberty, less muscular bodies and less facial and body hair compared to normal teens.
  • Small, firm testicles and penis.
  • Enlarged breast tissue (gynecomastia).
  • Weak bones.
  • Low Energy Level.
  • Difficulty expressing feelings or socializing.
  • Problems with readings, writings and spellings.
  • Attention problems.


  • Weak Bones.
  • Decreased facial and body hair.
  • Enlarged Breast tissue.
  • Decreased sex drive or sexual problems.
  • Infertility
  • Small testicles and penis.
  • Taller than average stature.


  • 48,XXYY

Occur in 1 in 18,000-50,000 male birth.

  • 48,XXXY


  • The Incidence of 49, XXXXY is 1 in 85,0000 to male 100,000 male births.


Mosaic or Mosaicism.

  • Mosaic or mosaicism donates the presence of two or more populations of cells with different genotypes in one individual who has developed from a single fertilized egg.
  • Males with Klinefelter syndrome may have a mosaic 47,XXY/46,XY constitutional karyotype and varying degrees of spermatogenic failure.
  • Mosaicism 47,XXY/46,XX with clinical features suggestive of Klinefelter syndrome is very rare. Thus far, only about 10 cases have been described in the literature.

Klinefelter Syndrome – postnatal diagnosis


Percentages of Klinefelter diagnosis divided by age groups, with most diagnoses occurring in adulthood.

Diagnosing Klinefelter Syndrome

The greatest chances to make Klinefelter diagnosing are in following times of life:

  • Before or shortly after birth
  • Early childhood
  • Adolescence
  • Adulthood

For males in which Klinefelter syndrome is suspected, a special blood test is recommended to confirm the Klinefelter syndrome diagnosis.


Blood test:

  1. Blood test called a karyotype and is the standard diagnostic method
  2. Test looks at a person’s chromosomes

Prenatal Testing:

  • Many males have been diagnosed through amniocentesis or chorionic villus sampling (CVS)
  • In amniocentesis, a sample of the fluid surrounding the fetus is withdrawn
  • CVS is similar to amniocentesis. The procedure is done in the first trimester (during the fist three month of pregnancy, it’s important to establish a foundation of good health) and the fetal cells needed for examination are taken from the placenta


Testosterone treatment should begin at puberty:

  • can normalize body proportions and promote development of normal secondary sex characteristics
  • but does not treat infertility, gynecomastia and small testes
  • By 2010 over 100 successful pregnancies have been reported using IVF (In vitro fertilization) technology with surgically removed sperm material from men with Klinefelter syndrome

The results of a study on 87 Australian adults with the syndrome shows:

  • Who have had a diagnosis and appropriate treatment from a very young age had a significant benefit with respect to those who had been diagnosed in adulthood

Also Read : Down syndrome