Turner's syndrome diagnosis
What is Turner's syndrome?
This is a condition that is caused by absence of one sex chromosome. A normal human being has 23 pairs of chromosomes, making a total of forty-six chromosomes. One of the pairs is made up of sex chromosomes. The female sex chromosomes are XX and the male chromosomes are XY. A woman is therefore represented as 46XX and a man as 46XY.
A Turner's syndrome person is represented as 45X0 (the 0 standing for a missing chromosome). Turner’s syndrome is also known by the descriptive term ‘Monosomy X’, meaning the individual has one X chromosome rather than the normal two for a female.
Is a Turner's syndrome individual male or female?
Female. There is a normal vagina, a uterus and tubes. The ovaries are, however, streaky and non-functional. This means a Turner's girl cannot ovulate. Nor can she conceive in the normal way.
Apart from the fertility aspect, what are the prospects for a Turner's baby?
Pretty good. In fact, in a good number of Turner's syndrome girls, the diagnosis is not made until their early or mid-teens. However, there are some physical characteristics which may arouse suspicion of something amiss. These may include short stature and a webbed neck. There may also be heart or kidney anomalies, which may lead to investigations for chromosomal defects. Intellectually, they tend to be of average intelligence.
What about Turner’s syndrome diagnosis before birth?
There are no biochemical or specific ultrasound diagnostic features for Turner's syndrome. There is, however, a lethal form of Turner's, where quite marked physical and heart abnormalities may be detected on ultrasound. Such pregnancies tend to end in miscarriage or stillbirth. This affects only a minority of Turner's syndrome babies. Of-course, if a mother undergoes an amniocentesis for whatever reason and the baby is affected by Turner’s syndrome, the diagnosis will be made by the chromosomal analysis.
Does maternal age influence the risk of having a Turner's syndrome baby?
No. The overall risk is estimated at one in 2500 and is constant at any maternal age. Paternal age, likewise, has no influence on the risk rate.
Klinefelter's syndrome diagnosis
What is Klinefelter's syndrome?
This is a chromosomal disorder where the affected individual has an extra X chromosome. The chromosomal constitution is therefore 47XXY instead of the usual 46XY. Because of the presence of the Y chromosome, the affected child is always male.
Can Klinefelter's syndrome be diagnosed antenatally?
Not normally. However, if a diagnostic test is performed for any other reason, the diagnosis of this condition will be established on mapping the chromosomal make-up.
What are the prospects for a Klinefelter's baby?
These individuals have fairly average prospects.
Physically, they attain normal height; they may even be taller than average. However, there is increased incidence of behavioural problems during adolescence.
They may also have mild learning difficulties.
Above-average breast development could pose a problem for an affected young man. More ominous is the fact that, compared to the average male, the risk of breast cancer is increased twenty times.