Congenital stupidity is one of the most common autosomal abnormalities in humans, with an incidence of 1/800 to 1/600. 1866, Langdone Down, an American physician, first described the clinical manifestations of the disease, so it was named Down syndrome, which is a congenital disease caused by an extra autosome 21, also known as trisomy 21. Chromosomes are the material basis for genetic information in the nucleus of cells, and human cells have 46 chromosomes (23 pairs). Of these, 22 pairs are autosomes or somatic chromosomes, which determine various traits in each person’s body; the remaining pair, called sex chromosomes, determines a person’s sex. Genetic disorders caused by abnormalities in the number or structure of chromosomes are called “chromosomal disorders,” or chromosomal abnormality syndromes. Because chromosomal abnormalities involve multiple organs and systems and have a variety of manifestations, they are called “syndromes”. What are the special manifestations of congenital dysgenesis? 50% of children with congenital dysgenesis die before the age of 5, 8% live past the age of 40, and only 2.6% live past the age of 50. The average life expectancy is only 16.2 years. The most serious and prominent manifestation is the obvious mental retardation, with an IQ of 20 to 50, poor abstract thinking skills, a docile personality, and a willingness to imitate, with the difference in intelligence widening with age. 2. 2. special facial features: small head, small eyes, wide eye spacing, upward slanting eye bags, strabismus, nystagmus; low nasal bridge, small jaw, low ear position, small ears; open mouth, salivation, stretched tongue. 3. developmental delay: large and late closure of the hallux valgus, short limbs, short metacarpals, hypoplastic, absent or inward curved middle finger, poor hearing, low muscle tone, etc. 4. Important organ malformations: 50% have congenital heart disease (ventricular septal defect, atrial septal defect, arteriovenous ductus arteriosus), duodenal stenosis and atresia, megacolon, rectal prolapse, anal atresia, tracheoesophageal fistula, etc. Males may have cryptorchidism, oligospermia, small penis, small scrotum; females usually have no menstruation (only a few are fertile). 5. Special changes in skin texture: more than 2/3 of the children with the disease have an increase in the atd angle of the palm, with the trigeminal point moving upward toward the palm, and 50% have a through palm; the bunion and second toe are widely spaced. There are many common congenital disorders in newborns. For example: congenital hypothyroidism, with a domestic prevalence of about 1/3800, phenylketonuria (PKU), about 1/58000, and b-thalassemia, about 1/10000. Comprehensive screening for these diseases has been started successively in China, and treatment or partial treatment is possible even if detected after birth. However, congenital stupidity children are different. The annual birth rate of congenital dysfunctional children is 1/800 to 1/600, and there are more than 20,000 children affected each year. Every pregnant woman has the possibility of giving birth to a child with congenital dysmorphic disorder, and this possibility increases with the age of the pregnant woman. The birth rate of congenital dysfunction is significantly higher in pregnant women over 35 years old, accounting for 30% of all births, while the remaining 70% are born to pregnant women under 34 years old. The birth rate is 1:1221 for 20-year-olds, 1:727 for 30-year-olds, and 1:385 for 35-year-olds, and up to 1:90 if they reach 40 years of age. Screening for congenital stupidity is a forecast, so the results reported are not like common medical tests, where the absolute value is obtained but the probability, that is, the degree of risk of having a child with stupidity. The best time to perform the maternal blood triple screening test is when 2 ml of fasting venous blood is drawn from 15 to 18 weeks of pregnancy (no later than 21 weeks). The software calculates the indicators of the maternal blood test to obtain the combined risk (also understood as the likelihood) of the child being born, and compares this risk with the empirical risk threshold; if the combined risk is less than the empirical threshold, the likelihood of the child being born is low; if the combined risk is higher than the threshold (1/270), the likelihood is high and a high level of vigilance is required. Ultrasonography to determine the number of weeks of gestation, and if a positive risk level still occurs, further amniocentesis and cytosolic chromosomal examination should be performed, which is the final confirmation of the diagnosis. Once the diagnosis is clear, the pregnancy should be terminated as soon as possible. After screening, the chances are less than the threshold, which means that the possibility of birth of a congenitally stupid child is small, but this does not absolutely guarantee that 100% of sick children will not be born, because there is still no screening method in the world that is 100% correct, and the positive rate of maternal blood triple screening has reached more than 75%, which is the most advanced and reliable screening method at present.