KLINEFELTER'S SYNDROME
This condition was first described in 1942 by Klinefelter and others
and in 1959 was shown to be due to an abnormality of the sex chromosomes.
It is now known to be remarkably common, affecting one in a 1,000 males,
many of whom do not know that they have the syndrome.
Cause:
Human cells contain 46 chromosomes, arranged in 23 pairs, one of each
pair inherited from the mother and one from the father. One pair of chromosomes
comprises the sex chromosomes, so called because one major function is
to determine the sex of the fetus. In women the sex chromosomes are both
X chromosomes but men have one X and one Y. Ova (eggs) normally contain
only one X chromosome and sperm either one X or one Y. Occasionally, due
to a genetic accident in which the chromosomes do not separate normally
as the ovum or the sperm develops, two X chromosomes are left in an ovum
or an X and a Y in a sperm so, if these are fertilised, the fetus will
develop as a male with two Xs and one Y chromosomes instead of the usual
XY. Such fetuses develop into males with Klinefelter's syndrome.
Features of the syndrome:
Boys with Klinefelter's syndrome are generally normal at birth and are
seldom recognised in early childhood although the testes may be rather
small and firm. In build they tend to be tall and long-limbed, especially
in the legs, this build may be become more obvious in puberty. At puberty
male development occurs but it can sometimes be incomplete with inadequate
development of the genitalia, musculature and beard. At puberty also some
boys also have somewhat excessive breast development. The testes remain
small and firm because the development of the "seminiferous tubules"
(the structures in the testes in which the sperm is formed) is abnormal.
The production of sperm is therefore absent or inadequate and men with
Klinefelter's syndrome are infertile. Intelligence is generally within
the normal range but there may be a tendency to some reduction in verbal
IQ scores. It has often been stated that men with Klinefelter's syndrome
are prone to have psychological and behavioural problems but population
screening, in which all the men with Klinefelter's syndrome in a population
are identified, has been reassuring, indicating that there is overall no
significant difference in behaviour from normal men.
Investigations:
The diagnosis is made by finding the typical XXY genetic constitution.
In some men there may be a "mosaic" state in which some cells
are XXY and others have a normal male XY pattern; as might be expected
such men tend to have less features of the condition. From mid-childhood
the testicular problem is reflected in blood tests by high levels of the
hormones from the anterior pituitary gland in the head which control the
function of the testes. Biopsy (removal of a very small piece of tissue)
of the testes shows the failure of development of the seminiferous tubules
but this is not needed to make the diagnosis.
Treatment:
Since this is a genetic condition present in all the cells of the body
no cure is possible so treatment has to be addressed to the problems that
can arise. The tall stature and long-limbed build is seldom sufficiently
great to cause cosmetic or other problems. If male development at puberty
is inadequate, additional male hormone can be given as capsules, injections
or, recently, skin patches. If there is excessive breast development at
puberty this can be completely corrected surgically. If special help with
schooling or behaviour is needed this can be of course be arranged. Sadly,
the infertility cannot be helped but couples now have the option of artificial
insemination with donor sperm.
Outlook:
Although it is concerning to learn of all the possible features of this
condition it is important to remember that they are seldom all present
and that most affected men make very good adjustment and have successful
and fulfilled lives with infertility the only major problem. |
