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Thursday, 13 December, 2001, 16:54 GMT
Sperm injection gene worries
In ICSI, a single sperm is injected into the egg
A fresh study has raised concerns about potential malformations in children conceived through the ICSI fertility technique.

The research, published in New Scientist magazine, makes links between men with genetic defects - who may need ICSI to have children - and rare problems such as "ambiguous genitalia", in which the genitals are neither obviously male or female.

However, as there is as yet no suggestion of this problem in extensive epidemiological studies on the health of ICSI babies, other scientists are likely to be sceptical.

Single shot

ICSI, which standards for intra-cytoplasmic sperm injection, involves using a single sperm to fertilise an egg.

It is a relatively new technique, and is still under the microscope to make sure that there are no long-term problems with children produced this way.

It is the only effective option for many men who have very low sperm counts, or whose sperm are not active enough to fertilise the egg.

Some men find themselves in this position because of illness or cancer treatment - but others have poor quality or too few sperm because of genetic problems.

One in 20 men

For perhaps 5% of men, the genetic problem are small discrepancies on their sex chromosome - the Y chromosome - called microdeletions.

In these cases, it is certain that these gene defects - and probably the associated fertility problem - will be passed on to any male offspring.

A slightly higher number of ICSI babies have been born with minor malformations of the genitals called hypospadias, and this is widely thought to be due to gene defects handed down from their fathers.

However, the latest research, from the Pasteur Institute in Paris, investigated a larger number of cells from men who had these "microdeletions" on their Y chromosomes.

They found that the entire Y chromosome was missing in some 10% of the cells taken from elsewhere in the body.

This means, they suggest, that microdeletion of information on the Y chromosome is a sign of wider genetic instability which could cause the entire chromosome to be absent from some cells.

In theory, any widespread loss of the Y chromosome cells could have more serious consquences - as it governs the formation of sex organs and other sexual characteristics.

Mosaic effect

In some cases, they say, the result could be "genetic mosaicism", which could cause conditions such as ambiguous genitalia.

However, these kinds of defects are apparent at birth, and any increase in the rate of such abnormalities would probably have been detected in the large-scale studies of the health of ICSI babies carried out in Europe and elsewhere.

And, apart from the slightly higher rate of hypospadias, there is no sign of any increase in malformations.

Dr Ken McElreavey, who conducted the Pasteur study, suggested that doctors offering ICSI should, however, be on the lookout for men with Y chromosome microdeletions.

See also:

24 Oct 01 | Health
Gene key to sperm power
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