Israel joins validation of test to detect Down syndrome
Israel to participate in validation of Cyprus doctor’s test to detect Down syndrome at early stage of pregnancy.
By JUDY SIEGEL-ITZKOVICHPROF PHILIPPOS PATSALIS 370(photo credit: Courtesy of Shalva)
The day is nearing when Down syndrome in a fetus can be diagnosed early and noninvasively with a simple blood test, as Israel joins a consortium of five European countries to validate such a test developed in Cyprus.It was learned on Thursday night that the Hadassah Medical Organization has become the first Israeli medical institution to be invited by Prof. Philippos Patsalis of the Cyprus Institute of Neurology and Genetics in Nicosia to collaborate on validation of the test. It will take more time for the health authorities in Europe and elsewhere to accept the accuracy and validity of the blood test and then for it to be marketed.Pregnant women at Hadassah may give consent now and volunteer to provide blood samples to be tested in cooperation with the Cypriots, but the results regarding their fetuses’ genes will not be provided to them or be used for decisions on whether to do an abortion.Down syndrome is a genetic disorder caused by an extra 21st chromosome.Patsalis appeared this week at a second conference on Down syndrome at Hadassah University Medical Center on Jerusalem’s Mount Scopus organized by a number of groups, including Hadassah and Shalva, a voluntary organization that takes care of and promotes the advancement of Down syndrome children. It was chaired by Dr. Ariel Tenenbaum, head of the Hadassah Center for Down Children.HMO has decided in principle that as soon as the blood test becomes commercially available, it will offer it to pregnant women who would otherwise need to undergo the invasive test of amniocentesis, in which placental fluid is rather painfully removed with a needle from the womb. This test also causes a woman to miscarry in one out of about 200 to 300 tests. Thus if a woman is pregnant for the first time at 40, she will think twice before agreeing to amniocentesis, even if she is at risk of having a fetus with Down syndrome.Over a year ago, the new blood test, revealed in a report in Nature Medicine by Patsalis and colleagues, showed almost 100 percent sensitivity and 100% specificity in all Down syndrome pregnancies, as well as all those with normal 21stchromosome fetuses.If the validation research shows that the blood test could identify Down syndrome in fetuses at 11 or 12 weeks with almost 100% accuracy, it could eventually significantly reduce the number of mentally disabled children born in Israel, because their mothers could undergo an early abortion.However, many Israeli parents – both Jews and Arabs, observant and secular – may continue to decline to abort such a fetus for religious or other reasons after such a test becomes available. But as there there will be some who regard the 11th week after conception as early enough according to Jewish law to perform such abortion, there would be fewer Down children born.Prof. Orly Elpeleg, a senior pediatrician and director of Hadassah’s genetic and metabolic disease department, told The Jerusalem Post on Thursday: “What is new is that it is very advanced stage of validation, and we are cooperating in this effort. The concept has been known for a very long time; everyone has ‘free DNA’ in the blood plasma. In pregnant women, there is a leak of free DNA into their own plasma.
The Cypriots did a lot of work to differentiate specific characteristics of the mother’s from the fetus’s free DNA so genetic differences could be detected.”Hadassah experts can already use this technique to know at the sixth week of pregnancy whether a fetus is male or female, but it is not permitted by the Health Ministry to use it except to determine sex-linked genetic defects that involve medical decisions.As the amount of free DNA is so small, the results from the blood test are not absolutely accurate, but it is as close to 100% as it has ever been from a noninvasive test.Eventually, it is believed that other genetic abnormalities will be detectable from this type of blood test, and it would become much cheaper and thus routine for every pregnant woman.Tenenbaum added: “This technique is a revolution. It will probably become commercially available in two years and relatively cheap. It will be a major change in the whole world. And it will make amniocentesis much less used.”
