A genetic condition that results when a male is born with an extra copy of the X chromosome causing males to have low testosterone levels and/or producing little or no sperm.
The condition is not from a parent , it is a random event.
It is common for this condition to be undiagnosed until adulthood.
Chromosomes are packages of genes found in every cell in the body. There are 2 types of chromosome, called the sex chromosomes, that determine the genetic sex of a baby. These are named either X or Y.
Usually, a female baby has 2 X chromosomes (XX) and a male has 1 X and 1 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.
NHS Choices
Cause
One extra copy of the X chromosome in each cell (XXY)- (common)
An extra X chromosome in some of the cells (mosaic Klinefelter syndrome), with fewer symptoms
More than one extra copy of the X chromosome (rare and severe form)
Risk of a woman having a son with Klinefelter syndrome may be slightly higher if the mother is over 35 years of age.
Source: HealthLink BC
Source: Genetics Home Reference - NIH
Symptoms
(Symptoms can vary)
Babies
General discomfort (muscle weakness), uneasiness or ill feeling (malaise) and/or fatigue (tiredness)?
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
Taller than average stature?
Longer legs, shorter torso and broader hips compared with other boys?
Absent, delayed or incomplete puberty?
After puberty, loss of muscle and/or muscle are shrinking?
Thinning hair or baldness on head?
Less facial and body hair compared with other teens?
Enlarged breast tissue/Change of size of breasts (gynecomastia)?
Small, firm testicles?
Small penis?
Brittle, soft weak bones, dental problems and/or prone to fractures or curved/bone legs and/or curved spine?
Low energy levels?
General discomfort (muscle weakness), uneasiness or ill feeling (malaise) and/or fatigue (tiredness)?
OMIM is intended for use primarily by physicians and other professionals concerned with genetic disorders, by genetics researchers, and by advanced students in science and medicine. While the OMIM database is open to the public, users seeking information about a personal medical or genetic condition are urged to consult with a qualified physician for diagnosis and for answers to personal questions.
Detailed Information
Please copy and paste any key words from the title: Klinefelter syndrome in the following respective 'Medtick References and/or Sources' to find out more about the disease (this also may include diagnosis tests and generic medical treatments).
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