Down Syndrome

Abstract:  Downs syndrome is a syndrome of intellectual retardation accompanied by abnormal facial features, which wills when a baby inherits troika copies of chromosome 21 instead of the normal both copies. This chromosome abnormality, c every(prenominal)ed trisomy 21, may be detect prior to suffer by culturing some cells from the foetus and examining the chromosomes straight off (karyotyping). However, this running game is time-consuming and costly, and is normall(a)y uncommunicative only for women at the superlative insecurity. Generally, this take chances is determined by the mothers be on; women all over 36 be considered to be at the highest risk. However, Downs syndrome is the most old(prenominal) of all chromosome abnormalities and affects nigh 1 in 700 births. Women over 36 account for only about 30 percent of all Downs syndrome births and, at present, only about 15 percent of the cases of Downs syndrome atomic bit 18 find before birth. It would be very valuable, therefore, to develop a screening method that would result in the prenatal wisdom of many fetuses with Downs syndrome without excessive cost. In a review of 3,436 pregnancies, 5 percent were karyotyped because of the mothers age and heritable history.

A summarize of cardinal affected fetuses were identified; the total may be considered 11, if leash cases born shortly afterwards the close of the study foreland in time are also considered. Only unrivalled of the affected fetuses was detected by conventional screening procedures. However, a new particularise of risk factors was designed that included the quantity of alpha fetoprotein and chorionic gonadotrophin in the mothers blood. The unobjectionable ranges were defined so that the number of karyotypes that would be recommended on the priming of these risk factors would be 5 percent, about the same as when maternal age is employ as the predominant risk factor. Using these criteria, 8 of the 11 affected pregnancies would behave been recommended for karyotyping, which would have yielded a espial position of 73 percent. The adoption of this method of using risk...If you indispensableness to discover a full essay, assign it on our website: Orderessay

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