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Monday, 26 June, 2000, 10:11 GMT 11:11 UK
Screening test for devastating disease
Lab equipment
Genetic test could reduce risk of disorder
A screening test carried out before IVF could prevent a condition which kills babies shortly after birth.

Ornithine transcarbamylase (OTCD) is a genetic disorder which prevents babies breaking down protein properly, leading to excessive amounts of toxic ammonia in the body.

Treatment immediately after delivery can prolong the life of a child with the condition - but a sufferer is still likely to die at any time.

Boys usually die soon after birth, while girls carrying the gene can die in the same period or suffer symptoms such as vomiting, lethargy, delayed growth and extreme irritability.

More extreme symptoms include seizures and comas.

Dr Pierre Ray, from the Hopital Necker Enfants Malades in Paris, told the conference that women who knew they carried the gene could potentially seek help from geneticists.

At present the condition can be detected in the foetus during pregnancy, but at that point the only option is termination.

Universal help

At present his team has only been able to help one French family, but they expect that a technique could be developed which could potentially detect the condition universally.

What the scientists did was to create embryos using IVF techniques, then analysing them prior to implantation.

Only healthy embryos would then be implanted and carried to term.

Dr Ray told the conference: "Diagnosis for OTCD is difficult because of its rarity and because new mutations of the OTC gene are quite frequent.

"This means that people who are affected by OTCD, or who are carriers, will have different mutations of the gene unless they are from the same family."

In the family studied by this project, six embyros were obtained after IVF, of which half were diagnosed as unaffected and implanted, although no pregnancy resulted.

A second attempt has been made, and results are awaited.

The condition affects boys more severely because the gene defect is on the X-chromosome, of which boys have only one copy.

In girls, there are two copies of the chromosome, although if both X-chromosomes are affected then the illness will certainly develop.

Ornithine transcarbamylase (OTCD) affects only one in 70,000 births.

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14 Jun 00 | Health
Discovery over pregnancy danger
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