What Is Prenatal DNA Testing?

Non-invasive DNA prenatal testing, also known as non-invasive prenatal DNA testing, non-invasive fetal chromosome aneuploidy testing, etc. According to the Board of the American Academy of Obstetricians and Gynecologists, an internationally authoritative academic organization, Non-invasive Prenatal Testing is the most widely used technical name. Non-invasive DNA prenatal detection technology only needs to take venous blood from pregnant women, use next-generation DNA sequencing technology to sequence free DNA fragments (including fetal free DNA) in maternal peripheral plasma, and analyze the sequencing results for biological information, which can be used to obtain the fetus. Genetic information to detect whether the fetus has three major chromosomal diseases.

Non-invasive DNA prenatal detection technology

Non-invasive DNA prenatal testing, also known as non-invasive prenatal DNA testing, non-invasive fetal chromosome aneuploidy testing, etc. According to the Board of the American Academy of Obstetricians and Gynecologists, an internationally authoritative academic organization, Non-invasive Prenatal Testing is the most widely used technical name. Non-invasive DNA prenatal detection technology only needs to take venous blood from pregnant women, use next-generation DNA sequencing technology to sequence free DNA fragments (including fetal free DNA) in maternal peripheral plasma, and analyze the sequencing results for biological information, which can be used to obtain fetus Genetic information to detect whether the fetus is suffering from three major

As a screening method for fetal chromosome aneuploidy, non-invasive prenatal DNA testing uses cell-free fetal DNA from pregnant women's plasma for testing. This DNA is also known academically as circulating free fetal DNA, with a concentration of about 3-13%. It is believed to come mainly from the placenta and is cleared from the mother's blood within hours after delivery. Noninvasive prenatal DNA analysis has been used clinically to detect fetal aneuploidy risk.

It was first reported in 1969 that fetal cells were found in maternal peripheral blood. After decades of research, it was found to be extremely low in content and to exist for a long time. These characteristics make its application in the field of prenatal diagnosis limited.

Medical institutions conducting prenatal screening and diagnosis of fetal free DNA from pregnant women's peripheral blood should obtain prenatal diagnostic techniques such as the "Maternal and Infant Health Care Technical Service Practice License".

Medical institutions that carry out prenatal screening and diagnostic blood collection services for fetal free DNA from pregnant women's peripheral blood (hereinafter referred to as blood collection institutions) shall be qualified prenatal screening or prenatal diagnosis institutions. Antenatal screening agencies that conduct blood collection services must establish cooperative relationships with prenatal diagnostic institutions, and report to the provincial health and family planning administration.

Medical institutions carrying out laboratory tests on fetal free DNA of pregnant women's peripheral blood (hereinafter referred to as testing institutions) shall have the qualification of clinical gene amplification laboratory, strictly abide by the "Administrative Measures for Clinical Laboratory of Medical Institutions" and "Clinical Gene Amplification of Medical Institutions" "Laboratory Management Measures" and other related provisions, the corresponding inspection items should be subject to the inter-room quality evaluation organized by the National Health and Family Planning Commission Clinical Inspection Center. ^[4]

Professional and technical personnel engaged in prenatal screening and diagnosis of fetal free DNA from pregnant women's peripheral blood should obtain corresponding qualifications in accordance with the "Administrative Measures for Prenatal Diagnosis Technology".

Laboratory personnel engaged in prenatal detection of fetal free DNA from pregnant women's peripheral blood should undergo clinical gene amplification testing technology training organized by the health and family planning administration department at the provincial level or above, and obtain a training certificate. ^[4]

When pregnant women under the following circumstances are tested, the accuracy of the test is reduced to a certain extent, and the detection effect is not clear; or in accordance with relevant regulations, they should be advised to perform prenatal diagnosis. include:

1. Early prenatal screening is high risk.

2. The age during the expected delivery period is 35 years.

3. Severe obesity (body mass index> 40).

4. Fertilization through in vitro fertilization-embryo transfer.

5. History of delivery of fetus with chromosomal abnormalities, except for couples with chromosomal abnormalities.

6. Twin and multiple pregnancy.

7. Other circumstances that the physician believes may affect the accuracy of the results. ^[4]

Testing of pregnant women in the following situations may seriously affect the accuracy of the results. include:

1. Pregnancy week <12 weeks.

2. The couple has a definite chromosomal abnormality.

3. Have received allogeneic blood transfusion, transplantation, allogeneic treatment, etc. within 1 year.

4. Ultrasound examination of the fetus indicates that structural abnormalities require prenatal diagnosis.

5. A family history of genetic diseases may indicate that the fetus is at high risk of genetic diseases.

6. Malignant tumors during pregnancy.

7. Other circumstances that the physician believes have a significant impact on the accuracy of the results.

Except for the above-mentioned inapplicable circumstances, pregnant women or their families can choose prenatal detection of fetal free DNA in the peripheral blood of pregnant women with sufficient informed consent. ^[4]

The significance of prenatal detection and prevention of birth defects

China is a country with a high incidence of birth defects. Among about 16 million newborns each year, children with congenital morbidity and disability account for 4% -6% of the total number of births each year. One fifth of children with birth defects. The Chinese government pays about 8.2 billion yuan each year for medical and social relief for children with Down syndrome. Most of the children with birth defects who survive are chronically disabled or mentally disabled and cannot be cured. This has caused a serious economy to society Burden, the psychological burden and mental distress caused to the family cannot be measured by money. The clinical application of non-invasive DNA prenatal detection technology will greatly contribute to the prenatal detection of birth defects in China.