[Health Science] 3.21 World Down Syndrome Day | Prevent Down Syndrome and Care for Children with Down Syndrome

There is a group of children whose lives have deviated from the normal track due to a difference in chromosomes, bringing huge changes to an ordinary family. Due to congenital disabilities caused by chromosomal abnormalities, they have a unique "international face" and are slower in movement, growth, and development than healthy people. However, they are also lively, cute, kind, brave, and enthusiastic. They are "Down syndrome patients", also known as "Down babies".

What is Down syndrome? How to prevent it? ... The following will introduce it to you in detail.

What is World Down Syndrome Day?

In December 2011, the United Nations General Assembly designated March 21 of each year as "World Down Syndrome Day" with the aim of calling on the whole society to increase awareness and attention to Down syndrome, promote marriage and childbearing at appropriate age, reduce the risk of Down syndrome, and scientifically nurture healthy new life.

The 21st was chosen because of the uniqueness of Down syndrome - there is an extra chromosome in the 21st pair. Since 2012, this event has been held every year in the hope of giving Down syndrome patients equal rights and dignity, and allowing them to fully and effectively enjoy human rights and fundamental freedoms. There are currently more than one million "Down syndrome babies" in my country, and their families face huge mental and economic pressures. Scientifically, the top priority in reducing the incidence of Down syndrome is prevention, that is, Down screening during pregnancy. This test is an important measure to reduce birth defects.

What is Down syndrome?

Down's Syndrome (DS), also known as 21-trisomy syndrome/congenital idiocy, is a congenital disease caused by an extra chromosome 21. It is the most common chromosomal disease in humans and the first confirmed chromosomal disease in humans. It mostly occurs by chance, but can also be caused by genetic factors. Down's syndrome is one of the most common birth defects in my country. In 1866, the British doctor John Langdon Down first described the characteristics of the disease, and later named it Down's syndrome after him, which is "Down's syndrome" in Chinese.

What are the clinical manifestations of patients with Down syndrome?

1. Special facial features

For example, the eyes are widely spaced, the root of the nose is low and flat, the palpebral fissure is small, the outer side of the eye is tilted upward, there is epicanthus, the outer ear is small, the tongue is fat and often sticks out of the mouth, and there is a lot of drooling. The stature is short, the head circumference is smaller than normal, the front and back diameters of the head are short, and the occipital part is flat and flat. The neck is short, the skin is loose, and the teeth are delayed and often misplaced. The hair is fine and soft and less. The limbs are short, the phalanges are short, and it is common to see through palm lines and straw sandal feet.

2. Low intelligence

It is the most prominent and serious manifestation of Down syndrome. Its mental retardation becomes more obvious with age, with an IQ of 25 to 50, and delayed motor and sexual development.

3. Fertility

Male Down syndrome babies will not be able to have children when they grow up to puberty, while female Down syndrome babies will have menstruation and may have children when they grow up.

4. Others

Children with this disease often have congenital heart disease and other malformations. Due to low immune function, they are susceptible to various infections, and the incidence of leukemia is 10 to 30 times higher than normal. If they survive to adulthood, they often develop symptoms of senile dementia after the age of 30.

What causes Down syndrome?

When many people hear about Down syndrome, they feel that it has little to do with them. This is not the case. Every healthy couple has the possibility of giving birth to a child with Down syndrome. The onset of Down syndrome is random and has nothing to do with education, status, etc. Although Down syndrome is a disease caused by abnormal genetic material (chromosomes), the parents of most "Down babies" are not also Down syndrome patients. It is just that some accidental errors caused the non-disjunction of chromosomes during the formation of reproductive cells, resulting in three chromosomes 21. A very small number of parents are phenotypically normal chromosomal balanced translocation carriers, and the risk of the disease when giving birth to the next generation will be greatly increased.

How to prevent Down syndrome?

Prenatal screening and prenatal diagnosis are effective measures to prevent the birth of children with Down syndrome. Couples with a history of Down syndrome should undergo prenatal diagnosis when they have another child. Sampling includes mid-pregnancy amniocentesis for analysis of amniotic fluid cells, mid-pregnancy embryonic chorionic villus cells, and mid-pregnancy umbilical cord blood lymphocytes.

How to conduct prenatal screening and prenatal diagnosis?

1. Down syndrome screening

In the second trimester (15 weeks to 20+6 weeks), peripheral blood is drawn from pregnant women to test the concentrations of alpha-fetoprotein and free human chorionic gonadotropin (Free-βHCG) in maternal serum. The risk factor of a Down syndrome baby is calculated based on other information of the pregnant woman (including gestational age, weight, age, etc.).

2.NT screening

Ultrasound screening of fetal nuchal skin transparent membrane thickness (NT), ductus venosus blood flow (DV), nasal bone (NB) and other ultrasound indicators is performed in the early pregnancy (11 weeks to 13+6). The more obvious the NT thickening, the higher the chance of fetal abnormality and the more serious the degree of abnormality.

3. Non-invasive DNA testing (NIPT)

Non-invasive DNA testing extracts free DNA from the peripheral blood of pregnant women and uses sequencing technology to detect chromosomal abnormalities in the fetus. It does not require fasting when collecting blood, and the test can be performed from 12 weeks of pregnancy.

4. Prenatal diagnosis

Amniocentesis is a prenatal diagnosis and the gold standard for determining whether the fetus has chromosomal abnormalities. All pregnant women with high risk of prenatal screening are recommended to undergo this test to diagnose whether the fetus has chromosomal abnormalities! The best time for testing: 18-24 weeks of pregnancy.

The following groups of people need prenatal diagnosis

1. Pregnant women whose expected age is ≥35 years old. 2. High-risk groups for prenatal screening (including NT examination, Down syndrome screening, non-invasive DNA test, these three types of screening are high-risk groups). 3. Pregnant women whose husband and wife are both carriers of single gene diseases or have a history of giving birth to children with single gene diseases. 4. Pregnant women whose one spouse has chromosomal abnormalities or has a history of giving birth to children with chromosomal abnormalities. 5. Pregnant women whose fetuses are suspected of having chromosomal diseases during prenatal examinations (such as B-ultrasound examinations indicating fetal structural malformations, intrauterine growth retardation, etc.). 6. Pregnant women with a history of adverse pregnancy and delivery or a history of contact with special teratogens. 7. Other situations where doctors believe that the fetus is highly suspected of having chromosomal abnormalities.