Down syndrome is a genetic abnormality that is explained by the tripling of chromosome 21. If a person normally has 23 pairs or 46 chromosomes, then with Down syndrome there is a triple amount of the 21st chromosome instead of the two.
The disease was first described by doctor John Down in 1866 and therefore named after the author.
Down syndrome is a fairly common pathology, it is observed in one child among 700-800 births. It is impossible to say who suffers most often from this genetic abnormality: boys or girls, the percentage of sick children is the same in both cases.
Characteristic manifestations of Down syndrome is a lag in mental and physical development (in particular, short stature).
There are three forms of chromosomal abnormalities in Down syndrome:
- trisomy – occurs in 90% of cases. Trisomy is the presence of an additional 21st chromosome: instead of the two put three. Occurs in violation of cell division in the process of development of the egg or sperm. A similar phenomenon is observed in all human cells;
- Mosaicism – only a part of the cells have an extra 21st chromosome, it looks like a mosaic of normal and pathological cells. This defect is associated with impaired cell division after conception. The frequency of the disease reaches 2-3%;
- translocation – rearrangement of part of the chromosome in the 21st pair. That is, there are only two chromosomes, as it should be, but only a section of one chromosome in the 21st pair is attached to the other (extra shoulder). The frequency of diagnosis is 4%.
To date, only two causes of Down syndrome have been identified.
The first is the age of the mother, and the older the woman becomes, the higher the risk of having a child with this pathology (after 30 years it is 1: 1000, and after 42 years – 1:60). This is due to the aging of the eggs: as you know, their number is laid during the period of the formation of the fetus.
Another, more rare, cause is heredity (Down syndrome by translocation type of the 21st pair of chromosomes). It becomes clear that closely related marriages have a certain value, as well as the presence of a relative with Down syndrome in the family. In addition, scientists note the connection between the age of the grandmother, in which she gave birth to a daughter, and the chance to get a grandson with Down syndrome. The older grandmother was, the higher the risk of having a grandchild with this anomaly. The value of the father’s age is also not denied (the risk factor is men over 45).
Diagnosis of Down syndrome is carried out even during pregnancy, at the stage of gestation.
An important indication is the age of a woman (30 years and older). In the first trimester spend Fetal ultrasound (in the period of 10-14 weeks) to determine the width of the neck and collar space (the norm is 2 mm) and the presence / absence of the nasal bone. These signs are not characteristic and do not give a 100% guarantee of the disease. Then blood test for hCG level is performed.
In the second trimester, for a period of 16–18 weeks, a triple test is conducted: determination of hCG, alpha- fetoprotein ( AFP ) and estriol . With reduced rates, women are placed in a high-risk group and recommend invasive examination methods:
- choriontsentez (chorionic villus biopsy for about 13 weeks);
- amniocentesis (analysis of amniotic fluid after 18 weeks, during the survey there is a high risk of abortion and infection);
- cordocentesis (fetal cord blood analysis, performed after 18 weeks).
After childbirth, the diagnosis is established on the basis of characteristic clinical signs and karyotype determination.
The doctor may suspect Down syndrome immediately after the birth of the child on the basis of characteristic signs. However, an accurate diagnosis is established after determining the karyotype (chromosome set).
“Dunyaty”, for the most part, have a flat face with a Mongoloid cut of the eye and a skull of a shortened rounded shape (brachycephaly). The presence of a vertical skin fold that covers the inner corner of the eye (epicantus) is noted on the eyes.
There are increased mobility of the joints and hypotonia, due to which the child’s mouth is ajar and the tongue is extended.
The back of the head of children is flattened, a shortened neck with a head of small size and vertically set ears with adherent lobes, there are dental anomalies.
Over the age of 8 years, eye diseases often develop ( cataracts, glaucoma ). The nose of the “Downey” is also flattened, often takes place strabismus and a short nose.
On the palm there is one transverse fold, and the little finger is shortened and curved.
Often these babies have congenital heart and digestive tract defects, symptomatic epilepsy and chest deformity.
Sick children can reach medium height, but often their physical development is lagging due to impaired skeletal development.
All patients with this pathology have mental retardation to one degree or another.
The treatment of Down syndrome is lifelong, it consists not in getting rid of chromosomal pathology, but in the treatment of associated diseases and malformations. For example, with congenital heart defects, surgery is performed.
A group of various medical specialists is involved in the treatment of “Down”: a pediatrician, a psychiatrist and a psychologist, a cardiologist, a gastroenterologist, an endocrinologist, a speech therapist, an optometrist, a dentist, and others.
Parents of children with Down syndrome should understand and know that this anomaly is not a sentence, and, moreover, no one is guilty of having such a child.
The main treatment is aimed at social and family adaptation. With careful care and patience, children learn simple human skills (sit, walk, talk). They can attend both general education and special schools (preferably both). In ordinary school, a child learns to communicate with other children, develops and seeks to imitate classmates in everything. Subsequently, these children can receive secondary vocational education. The main thing in the care of a special child is the attention and love of parents.
To support the central nervous system, “Downyatas” are prescribed drugs that improve blood circulation in the brain:
- Cerebrolysin ;
- piracetam ;
- B vitamins;
- aminolone .
Complications of Down syndrome include:
- congenital heart defects;
- infectious diseases;
- early dementia ( Alzheimer’s disease );
- respiratory arrest during sleep;
The life expectancy of people with this pathology is low, about 49-50 years, but recently it has increased: even in the twentieth century, such patients lived for about 25 years. They are able to create families, but men cannot have children. As a rule, people with Down syndrome receive secondary education and work.