Symptoms of Poly-X Klinefelter syndrome

Symptoms of Poly-X KS [11]

Males with poly-X Klinefelter syndrome have more than one extra X chromosome, so their symptoms might be more pronounced than in males with KS. In childhood, they may also have seizures, crossed eyes, constipation, and recurrent ear infections. Poly-KS males might also show slight differences in other physical features.

Some common additional symptoms for several poly-X Klinefelter syndromes are listed below.


48,XXXY (or tetrasomy)

  • Eyes set further apart
  • Flat nose bridge
  • Arm bones connected to each other in an unusual way
  • Short
  • Fifth (smallest) fingers curve inward (clinodactyly, pronounced KLAHY-noh-dak-tl-ee)
  • Lower IQ, average 40 to 60
  • Immature behavior

49,XXXXY (or pentasomy)

  • Low IQ, usually between 20 and 60
  • Small head
  • Short
  • Upward-slanted eyes
  • Heart defects, such as when the chambers do not form properly12
  • High feet arches
  • Shy, but friendly
  • Difficulty with changing routines

Source: NICHD (NIH)1

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Read more about symptoms of related disorders:

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  1. Source: NICHD (NIH): health/ topics/ klinefelter/ conditioninfo/ Pages/ symptoms.aspx

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