Klinefelter syndrome

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Noun1.Klinefelter syndrome - syndrome in males that is characterized by small testes and long legs and enlarged breasts and reduced sperm production and mental retardation; a genetic defect in which an extra X chromosome (XXY) is present in the male
syndrome - a pattern of symptoms indicative of some disease
References in periodicals archive ?
Chromosomal abnormalities include Klinefelter's Syndrome, where an XXY male usually has small testes.
When a sperm having both an X and a Y chromosome fertilizes an egg having a single X chromosome, or a normal Y- bearing sperm fertilizes an egg having two X chromosomes, an XXY male is conceived.
A physician may suspect a boy is an XXY male if he is delayed in learning to talk and has difficulty with reading and writing.
At this time, an examining physician may note the undersized testes characteristic of an XXY male.
In another genetically engineered mouse model the researchers linked the X and Y chromosome so this pair could be matched up with an X chromosome, resulting in genetically XXY males.
Although previous reports have noted more cognitive and behavioral problems in XXYY males than in XXY males, this is the first study to directly compare the cognitive and behavioral features of the two syndromes, Dr.
XXYY males were found to have significantly lower verbal and full-scale IQs compared with XXY males, but there were no significant differences between the two groups on mean performance IQ scores, said Dr.
Studies have also found many XXY males have a degree of language impairment.
The full syndrome identified by Dr Harry Klinefelter (gynecomastia, testicular atrophy, azoospermia, and sparse facial and body hair) is not found in the majority of XXY males.
As in our patient, XXY males may not be diagnosed as such until adulthood, if at all.
In his studies on XXY males, Charles Netley of the Hospital for Sick Children in Toronto suggests that this social withdrawal, as well as language difficulties, correlates with increased right hemisphere activity.
Bender reports that XXY males have a slight but statistically significant deficit in IQ, while XXX females have a larger deficit, similar to that in Turner's syndrome.