March 21, 2022 is the 11th "World Down Syndrome Day", the theme of the publicity campaign is "Attach importance to Down's screening, pregnant with healthy babies", aiming to improve the awareness and attention of the whole society on Down syndrome, guide women to take the initiative to accept Down's screening after pregnancy, do a good job in pregnancy health care, and scientifically conceive healthy new life.
Down syndrome, also known as trisomy 21 syndrome, is a severe chromosomal disease caused by abnormalities on chromosome 21, and it is also the earliest identified chromosomal disease in humans. The main clinical features of pediatric Down syndrome are intellectual disability, developmental delay, special facial features, and can be accompanied by multiple malformations, which can be confirmed by karyotype analysis. There is currently no effective treatment for Down syndrome in children, and mothers of childbearing age can prevent it with regular check-ups before and during pregnancy.
Our city uses molecular genetic technology such as high-throughput gene sequencing to detect free FETAL DNA fragments in maternal peripheral blood during pregnancy to assess the risk of common chromosomal aneuploidy abnormalities in fetuses, strengthen the secondary prevention of birth defects, effectively reduce the birth of Down's children, and play an important role in controlling birth defects and improving the quality of the birth population.
Since 2019, the city has launched the fetal chromosome aneuploidy non-invasive prenatal screening (NIPT) project, pregnant women in the 12 weeks of pregnancy to 22 + 6 weeks, can be in all districts of maternal and child health care institutions, the municipal women and children's health care center, the central obstetrics and gynecology hospital, Tianjin Medical University General Hospital, the city's first central hospital and other four prenatal diagnostic institutions for intranatal blood collection, by the prenatal diagnostic institutions for testing and consultation guidance. In 2021, the city screened nearly 60,000 pregnant women, and found 77 cases of high risk of trisomy 21, with a detection rate of more than 90%, which avoided the birth of Tang's children to the greatest extent.
Down syndrome
Prevention and treatment of health education core information
First, Down syndrome is a serious birth defect and is the most common chromosomal disease.
(1) Down syndrome, also known as trisomy 21 syndrome, is the most common chromosomal aneuploidy abnormality, caused by one more chromosome 21 of human cells.
(2) Patients with Down syndrome have serious and irreversible intellectual disabilities, cannot take care of themselves in life, and need to be cared for for for a long time, often referred to as "Tang's children" and "Tang babies".
Second, the right age to give birth can reduce the risk of Down syndrome.
(1) The incidence of Down syndrome is 1/800 to 1/600, which is caused by the non-separation of chromosome 21 during meiosis of germ cells, and the aging of eggs of elderly mothers is an important reason for the occurrence of chromosome non-separation.
(2) The risk of Down syndrome is related to the mother's age of childbirth, which increases with the mother's age, and the father's advanced age increases the risk of other genetic diseases in the offspring. Promote age-appropriate childbearing and avoid pregnancies at an advanced age.
Third, Down syndrome is mainly manifested as intellectual disability, growth retardation and special appearance.
(1) Patients with Down syndrome have obvious special appearances at birth, such as small bleral fissure, wide eye distance, low nose bridge, low ear position, etc., often opening their mouths and extending their tongues, salivating a lot.
(2) Most of the children have different degrees of intellectual disability, growth retardation, and may be accompanied by congenital heart disease and other malformations, it is recommended that Tang children undergo echocardiography after birth.
(3) The diagnosis of Down syndrome requires genetic examination and diagnosis by means of chromosomal karyotyping and other examination methods.
Prenatal screening and prenatal diagnosis are effective ways to prevent Down syndrome.
(1) Down syndrome is caused by chromosomal abnormalities, and there is currently no radical cure, which should be actively prevented.
(2) On the basis of doing a good job in pregnancy health care, pregnant women routinely receive prenatal screening and necessary prenatal diagnosis, and timely intervention in Down children found during pregnancy is an effective method and an important strategy for preventing Down syndrome.
5. Every couple has the possibility of conceiving a Down child, and pregnant women of appropriate age should also receive routine Down screening.
(1) Most of the occurrence of Down syndrome is sporadic, and pregnant women of appropriate age should also have the informed choice of prenatal screening for Down syndrome (referred to as Down's screening) to assess the pregnancy risk of Down's children.
(2) Currently widely accepted maternal peripheral blood Down screening includes serological screening and maternal peripheral blood fetal free DNA testing (also known as noninvasive DNA testing, NIPT). Serological screening is divided into first-trimester (9 to 13+6 weeks of pregnancy) screening and second-trimester (15-20+6 weeks of pregnancy) screening, and the screening results are divided into high-risk, critical-risk and low-risk. The appropriate gestational age for noninvasive DNA testing is 12 to 22+6 weeks, and the screening results are classified as high and low risk.
6. Pregnant women with suspicious abnormalities in serological Down's screening results should go to a qualified medical institution for prenatal diagnosis.
(1) Pregnant women at high risk of serological Down screening need to receive genetic counseling and prenatal diagnosis, and take targeted medical interventions based on the results of prenatal diagnosis.
(2) Pregnant women at critical risk of serology Down screening are recommended to go to a qualified medical institution, receive genetic counseling, and knowingly select noninvasive DNA testing.
(3) Prenatal diagnosis is a special technology for maternal and child health care, medical institutions and technicians carrying out prenatal diagnosis need to approve and permit, and pregnant women should go to medical institutions with corresponding qualifications to receive prenatal diagnosis and non-invasive DNA testing.
Noninvasive DNA testing is only a screening method and is not a substitute for prenatal diagnosis.
(1) Noninvasive DNA testing is to assess the risk of common chromosomal abnormalities such as Down syndrome in the fetus by detecting free DNA fragments of the fetus in the peripheral blood of pregnant women.
(2) Non-invasive DNA testing is a high-precision screening method between serological screening and prenatal diagnosis for risk assessment of the target disease, and cannot replace prenatal diagnosis.
(3) Non-invasive DNA test results cannot be used as a basis for terminating pregnancy, and those with high risk of test results need to receive interventional prenatal diagnosis and follow-up genetic counseling.
8. Serologic Down screening or non-invasive DNA testing low-risk pregnant women still need to receive prenatal examinations, ultrasound examinations and other pregnancy health care services.
(1) Due to the existence of different degrees of false negatives in serological screening and non-invasive DNA testing, low-risk patients may still have the possibility of conceiving Down children and other children with abnormal chromosomal abnormalities.
(2) Down children are sometimes accompanied by some ultrasound soft indicators abnormalities or structural abnormalities, such as neck transparent layer (NT) thickening, heart malformations, etc., so down screening or non-invasive DNA testing low-risk pregnant women should do a good job of pregnancy health care, routine prenatal examination and fetal ultrasound examination, etc., if there is abnormality, interventional prenatal diagnosis should be carried out in time.
High-risk groups should receive genetic counseling before pregnancy and undergo prenatal diagnosis directly after pregnancy.
(1) High-risk groups with the following circumstances should go to a medical institution to receive genetic counseling and fertility guidance before pregnancy: advanced pregnancy, family members with genetic diseases, carriers of abnormal chromosomes, children with genetic diseases or birth defects who have given birth, bad maternal history such as repeated miscarriages or stillbirths, exposure to teratogenic substances and harmful environments and other high-risk factors, and so on.
(2) After high-risk groups become pregnant, they should go to a qualified prenatal diagnostic institution to receive genetic counseling and prenatal diagnosis services, and if necessary, conduct genetic examinations such as karyotyping of the fetus.
10. Parents with Down syndrome have a higher risk of having Down children than normal people, and they need to scientifically arrange their birth plans on the basis of genetic counseling.
(1) Most of the Tang children have no male fertility, and only a few women have fertility, but the incidence of chromosomal abnormalities in their offspring is high.
(2) Parents of Tang children should go to a qualified medical institution to receive genetic counseling and fertility guidance before giving birth again, and conduct chromosomal examinations. With the development of assisted reproductive technologies, preimplantation genetic testing (PGT) provides an option for such families with chromosomal abnormalities in both couples to conceive healthy babies.
(3) Preimplantation genetic testing (PGT), commonly known as "third-generation IVF", is an assisted reproductive technology for couples carrying certain known genetic disease genes, on the basis of in vitro fertilization technology, selecting some cells from the blastocyst as samples for genetic testing, screening embryos that do not carry pathogenic genes for transplantation.
11. Tang children should receive regular child health services and routinely undergo vaccination.
(1) Children of Down's can be vaccinated with all conventional vaccines, and children with severe chronic diseases and neurological diseases can be vaccinated as planned after their condition is stable. Down's children should be cautious about receiving live attenuated vaccines.
(2) Tang's children have low immunity, need to do a good job in child health care, pay attention to the prevention of infection, such as accompanied by congenital malformations, can consider surgical correction.
12. Comprehensive measures, including medical and social services, need to be taken to improve the social life capacity of people with Down syndrome.
(1) Comprehensive measures need to be taken to patiently educate and train patients with Down syndrome to improve the quality of life of patients and their ability to adapt to society.
(2) Most provinces have incorporated prenatal screening and diagnosis, including Down's screening, into local livelihood policies for pregnant women of appropriate age, and some charitable aid organizations have also actively participated in publicity and education, child rescue and other related work, please consult local medical institutions and health administrative departments for details.
(3) In 2011, the United Nations General Assembly designated March 21 as "World Down Syndrome Day", and since 2012, it has held relevant activities every year to raise public awareness of Down syndrome and advocate that the whole society respect and treat down syndrome patients with kindness.
Contributed by: Women's and Children's Health Division
Editor: Meng Fanjin