Turner syndrome

Turner Syndrome is a genetic defect that affects girls only. It was first described in 1938 by Dr Henry Turner. It affects about 1 in 2,500 baby girls born. It is a genetic condition and is due to the absence or altered pattern of one of the X chromosomes in the cells of the body.

Chromosomes
Normally each cell has twenty-three pairs of chromosomes. One of these pairs, the sex chromosomes, determines whether a baby will be a boy or a girl. In a girl there will be two Xs (46XX), however in Turner syndrome, one of the X chromosomes will be missing or altered slightly.

Turner syndrome
When an X chromosome is missing or different in all cells, this is described as 'classical Turner syndrome'. If the second X chromosome is missing or different only in some cells of the body, this is called 'Turner mosaicism'. Having only one X chromosome does not make a girl with Turner syndrome any less feminine than a girl who does not have Turner syndrome.

Purely by chance
Nobody knows the reason why some girls will be born with Turner syndrome and there does not appear to be anything parents can do to avoid one of their daughters having the condition. It happens purely by chance.

Diagnosing Turner syndrome
Turner syndrome can be diagnosed at any age from birth to adulthood. To diagnose the condition the doctors have first to suspect it – usually they are alerted by some physical features.

Some girls are diagnosed shortly after birth because they have puffy hands and feet or a heart problem, but if these features are not present the diagnosis may not be suspected.

Many girls are diagnosed during childhood because they are smaller than their friends or their brothers and sisters, or because growth checks show that they are growing slowly.

If no-one suspects they have Turner syndrome it may be missed until puberty is delayed, as that can be another clue. Some young women are not diagnosed until they seek help because they have not started their periods.

As with any condition, the amount and severity of features associated with Turner syndrome varies widely from individual to individual. Everybody is different.

Physical characteristics
Turner girls may have physical traits which are characteristic of the condition. At birth between a third and half of girls with Turner syndrome will have cushion-like swellings on the back of their hands and feet. This normally disappears after a while but may reappear during puberty.

Some girls with Turner syndrome may have a high narrow palate and smaller lower jaw which may lead to eating difficulties such as reflux. Nails often bend away from fingers and toes in a characteristic way and have a tendency to snag in socks.

Many girls have a greater than usual number of 'beauty spots', frequently on their face. Another rarer feature of Turner Syndrome is a webbed neck. This is a small fold of skin at either side of the neck giving the impression that the neck is short.

Physical problems
A small percentage of girls with Turner syndrome have some form of heart abnormality. Fortunately, most of these abnormalities are relatively insignificant but there are some that require surgery. Ear problems may also occur in patients with Turner syndrome, with a tendency to frequent infection of the middle ear. Later in life, some women with Turner syndrome may have a hearing impairment. Girls with Turner syndrome may also have minor kidney abnormalities, however these usually do not affect the functioning of the kidneys.

Stature
At birth, girls with Turner syndrome are usually a little shorter and weigh a little less than other girls. During the first couple of years of their lives, these girls grow almost as fast as their contemporaries but over time the difference in height becomes more apparent. This difference is particularly noticeable when other girls are experiencing puberty and rapid height increases which do not occur in girls with Turner syndrome.

Pubertal development and menstruation
Most girls with Turner syndrome will need help to bring on puberty, as in the majority of girls the ovaries have stopped functioning by this age. The ovaries normally perform two functions - storing eggs and producing the hormones oestrogen and progesterone. Oestrogen is necessary to begin the process of puberty. There are a few girls with Turner syndrome who do go through puberty without needing intervention, but sometimes puberty starts spontaneously and then becomes 'stuck'.

Typically, girls will receive treatment with oestrogen to start and/or maintain puberty. Towards the end of puberty a second hormone, progestogen, is added to allow the monthly withdrawal bleed (monthly period) that keeps the womb healthy.

Future fertility
Although treatment with oestrogen and progestogen will allow a girl with Turner syndrome to go through puberty and enable her womb to mature, her ovaries will not function. This means that most women with Turner syndrome are only able to have children with medical help.

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