INTRODUCTION
Klinefelter syndrome occurs in males as a result
of one or more additional X chromosomes. Instead
of the usual (diploid) male karyotype 46XY, the karyotype
for Klinefelter syndrome can be 47XXY, 48XXXY, or
49XXXXY.
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ANTENATAL
There are no distinguishing features of Klinefelter
syndrome on ultrasound although cystic hygroma have
been reported in some cases.
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POSTNATAL
Affected males are usually tall with relatively
long limbs and poor muscle development. Pubertal
development is normal but testicular size decreases
after puberty (hypogonadism) and many cases remain
undiagnosed until this time. Males suffer from azoospermia
and are therefore infertile. The development of secondary
sexual characteristics is also affected. Boys can
exhibit gynaecomastia (male breasts resembling female)
and the risk of breast cancer is the same as for
females. Although sexual function is normal libido
and sexual activity are reduced and beard growth
is minimal. Testosterone levels may be reduced and
levels of follicle stimulating hormone gonadotrophin
and are increased. Children can be treated with testosterone
before school age.
Life span is not reduced and IQs are within normal
range. However, there is some evidence to suggest
that intellectual development is delayed and individuals
have some educational difficulties and behavioural
problems.
Those with the rarer karyotypes 48XXXY, or 49XXXXY
are more severely affected. Growth deficiency, hypogenitalism,
and mental retardation are more pronounced. With
karyotype 49XXXXY, infants are severely mentally
retarded. Facial features include hypertelorism,
epicanthic folds, a broad nose, and a large open
mouth. Other associated skeletal anomalies include
radio-ulnar synostosis at the elbow and clinodactyly.
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WEST MIDLANDS
DATA
To be added
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