Turner syndrome

Turner syndrome is also called 45, X or XO syndrome, being a chromosomal condition found only in females. The foetus only has one copy of the X chromosome, with incidence reasonably common – one in every 2,000 live female births.

The features all occur together to create a picture in Turner syndrome, with some women having varying degrees of symptoms. Diagnosis of Turner syndrome may not be made until puberty.

Symptoms of Turner syndrome

• Lack of breast development
• Shorter in stature (about 20cm shorter than other women)
• Don’t menstruate
• Less or no pubic hair
• Normal intelligence
• May have puffy hands or feet at birth, and this swelling may last months or years
• About 45 per cent may have skin folds that look like webbing in the neck
• Sucking and feeding difficulties due to high arched palate in the first months of life – frequent regurgitation and vomiting
• Slow to grow at expected rate in first few years of life
• Chronic middle ear infections
• A constriction or stenosis of the aorta
• Heart valve abnormalities
• Emotional immaturity
• Kidney changes
• Learning problems – non-verbal/spatial (maths)
• Infertility (underdeveloped ovaries)
• Five per cent will menstruate but pregnancy is rare
• Higher than average miscarriage and birth abnormality rates

How does Turner syndrome happen?

When an egg and sperm cells are formed, the chromosome pairs separate to make only one pair of the cells, so 23 instead of 46. When an egg is fertilised, the egg and sperm come together to then form 46 chromosomes once again – one set from the mother and one set from the father.

Sometimes, however, when the egg and sperm form, an error occurs whereby the chromosome pairs separate in a disordered fashion. Some egg and sperm have 22 chromosomes, while others might have 24. If this occurs, when the normal 23 chromosomes pair up at conception, the resulting foetus has 45 chromosomes instead of 46. It’s this missing chromosome – known as monosomy – that leaves one chromosome unpaired. In Turner syndrome, this is the missing X chromosome.

There is usually no family history, since women with Turner syndrome can’t reproduce. It’s typically a one-off. The test for Turner syndrome can be performed while the foetus is in the womb.