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Introduction

1. What is non-invasive prenatal DNA testing?

Non-invasive prenatal DNA testing is a new type of testing technique targeted at numerical abnormalities of chromosomes for fetuses. Adopting a new generation of high-throughput sequencing technology combined with bioinformatic analysis, the test helps detect and analyze cell-free DNA in pregnant women’s peripheral blood. Non-invasive prenatal DNA testing is a safe, accurate and fast testing technique. 


21-trisomy syndrome (Down's syndrome), 18-trisomy syndrome (Edwards syndrome) and 13-trisomy syndrome (Patau syndrome), all of which show high incidence currently, are covered by non-invasive prenatal DNA testing.


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Fig 1: Application scope of non-invasive prenatal DNA testing


2.Technical principle

In 1997, researchers from Chinese  University of Hongkong found that there existed cell-free fetal DNA in the plasma and serum of pregnant women’s peripheral blood. This makes it possible to detect chromosomal disorders of fetuses by checking pregnant women’s peripheral blood.


High-throughput sequencing technology enjoys fairly rapid growth in recent years, and features high throughput and low cost compared with traditional sequencing techniques. With the technology, dozens to hundreds of GB of data are generated in each experiment; and the cost of single nucleic acid sequencing falls drastically. 


Moreover, features such as high accuracy and sensitivity enable wide application of high-throughput sequencing technology to human health.


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Fig 2: Cell-free fetal DNA contained in mother’s peripheral blood


Take the detection of Down's syndrome for example. According to studies, pregnant women with Down's syndrome fetuses show slightly higher content levels of No. 21 chromosome in their peripheral blood than normal pregnant women, because fetuses with Down's syndrome have one more No.21 chromosome than healthy fetuses.


The risk of a subject to bear a Down's syndrome baby can be evaluated after the relative content of No.21 chromosome in peripheral blood is tested, and content levels of No.21 chromosome in the peripheral blood of both the subject and ordinary pregnant women are analyzed. Combined with new generation high-throughput sequencing technology, non-invasive prenatal DNA testing ensures greatly higher sensitivity and accuracy as well as significantly shorter test period.


Tips

1.Test preparation   

Fasting is not required for blood drawing. Keep normal diet and daily schedule.


2.Test period

Professional test report is issued within 10 days after blood collection.


3. Channel of reservation

Hospital: obstetrician of cooperative hospital.

Tel: 4008-986-989 (customer service hotline)

Official website: http://www.annoroad.com/order_online


4. Insurance    

Annoroad buys insurance for all the pregnant women who are to take non-invasive prenatal DNA testing so that every one of them can be more assured.


About Down's syndrome

Down's syndrome is the most common chromosomal disorder of aneuploidy. With an incidence rate of 1/600-800, Down's syndrome is the primary cause of mental retardation for newborns. Since patients have one more No.21 chromosome than healthy people, the syndrome is also known as 21-trisomy syndrome.


Children with Down's syndrome have special facial features, short figure, mental retardation, no self-care ability, and multiple system complications. They suffer tremendously from physical illness and discrimination. Each family with a Down's syndrome child bears enormous psychological burden and economic pressure. 


In China, 26,600 babies are born with Down's syndrome annually, that is, one such newborn every 20 minutes. Currently, there are more than 600,000 cases of Down's syndrome nationwide. Over 100,000 yuan is needed for treating every newborn with Down's syndrome.


Down's syndrome is a fortuitous condition. The older the mother-to-be is, the higher the incidence of Down's syndrome for the baby. Every couple faces the risk of having a baby with Down's syndrome, which is impossible to prevent before pregnancy. Under the medical conditions nowadays, no effective treatment is available for Down's syndrome. It is wise and necessary to take a prenatal checkup during the course of pregnancy. This helps detect Down's syndrome, take efficient measures, and minimize the occurrence of Down's syndrome to newborns.

Fig 3: Relation between mother’s age and Down's syndrome incidence



 

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