A cheaper and quicker method of blood sampling rather than collecting fluid from the womb will be available to all pregnant women in 2013 to help diagnose Down's syndrome, says a new report.
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NICOSIA: A non-invasive, quick and low risk procedure based on maternal DNA could be generally available to pregnant women by 2013 to cheaply diagnose Down’s syndrome, said a Cyprus researcher.
Patsalis said the cheaper and quicker method of blood sampling rather than collecting fluid from the womb will encourage more couples to take the test and therefore slowly eradicate the disease.
"Down's Syndrome, or Trisomy 21, is the most common cause of mental retardation with an incidence of one in 600 births," Philippos Patsalis of the Institute of Neurology and Genetics in Nicosia told reporters. "This method can apply to all pregnancies, not only those at risk," he added, describing it as "one of the most important milestones in the history of the institute."
Improving on 1% foetal loss
"There is no cure, so this is a test for couples who want to know and prevent it, they are the ones who must decide on the fate of the pregnancy."
Invasive procedures currently used for prenatal diagnosis in the 16th week of pregnancy – which involve the use of a needle which passes through the womb to collect placental cells or some of the fluid that bathes the foetus - pose a 1% risk of foetal loss. The diagnosis is therefore only made available to high-risk women, and approximately 80% of the Down’s syndrome instances are picked up.
"Over the last few years, scientists have been looking for a new, non-invasive method, offered to all pregnancies and not associated with any risk of miscarriage," the 48-year-old doctor said.
Test provides 100% sensitivity
The study involved the collection of 10ml of blood from the 11-14th week of gestation from 80 pregnant women, of which 34 were from pregnancies carrying a foetus with Down’s syndrome and 46 carrying a foetus without.
All normal and all Down’s syndrome cases were correctly identified providing 100% specificity and 100% sensitivity. The study involved scientists in Cyprus, Greece and Britain using a sample of women with Greek ethnic origin.
The preliminary report, published in the journal Nature Medicine, is the latest of several recent studies that indicate scientists can detect Down's syndrome through simple DNA blood tests.
Modifiying test to include other diseases
Patsalis said the new test would be faster as it could take less than five days to obtain results, while not requiring specialised or complex lab equipment or know-how. "The test can be easily introduced into every genetic diagnostic lab in the world," he said.
Down's syndrome is caused by having an extra copy of chromosome 21 and the risk increases as a woman gets older. Currently, pregnant women receive blood tests and ultrasound to find out if the foetus is at risk before invasive action is taken for a definite diagnosis.
A larger scale clinical study using 1,000 women of different ethnic origin - to test the current 100% accuracy levels - is now being prepared to take place in Europe, Japan, Australia and the United States.
Patsalis said his team is also researching modifying the method so it can be used to test for other genetic diseases such as cystic fibrosis.
