In people with Down syndrome (trisomy 21), the 21st chromosome is completely or partially present in triplicate. Down syndrome is characterized by malformations that affect organs and tissues . How severe these are differs from child to child. Early individual support increases the chances of a normal and independent life.
Below you will find further information and selected specialists for Down syndrome.
Originally, experts referred to Down syndrome as Mongolism. However, this term is now obsolete.
Around 50,000 people with Down's syndrome live in Germany. Every year, 1,200 babies are born with a chromosomal abnormality. This means that around one in 500 children has the characteristics of Down's syndrome.
As the father or mother are not carriers of trisomy 21, Down's syndrome is not a hereditary disease.
The reason for the chromosomal abnormality is disorders in meiosis (maturation division of cells). The egg and sperm cells develop from precursor cells during meiosis. They usually have a normal double set of chromosomes (46 chromosomes).
A chromosome is a molecule that contains the genes and therefore also the genetic information. A normal chromosome set consists of 22-pair autosomes (which are not involved in sex determination) and two sex chromosomes.
Normally, the genetic information of the chromosomes is distributed evenly between egg and sperm cells during meiosis. This results in a single set of chromosomes with 22 autosomes and one sex chromosome. If the egg cell is fertilized later by a sperm, a cell with a double set of chromosomes is formed again.
However, errors can occur during cell division of the germ cells. If both copies of a chromosome end up in the germ cell, it has one chromosome too many.
In this case, there will be 47 chromosomes instead of 46 at a later fertilization. In Down syndrome, this applies to chromosome 21.
The maldistribution of this 21st chromosome during the formation of the egg is presumably related to the age of the mother. The risk of Down's syndrome increases with the age of the mother at fertilization. Other risk factors that contribute to the occurrence of trisomy 21 are also being discussed.
These include
Whether these factors really have an influence is highly controversial.
The extra chromosome 21 leads to various organ and tissue malformations. The extent to which these are pronounced varies from child to child.
However, the characteristic appearance is the same for all children:
Body growth is usually slower. They also have less muscle tone and delayed reflexes.
Patients with Down syndrome often have other physical deformities. For example, 50 percent of those affected have a heart defect. Many suffer from constrictions in the small intestine or rectum. People with trisomy 21 also have an increased risk of leukemia. Children with Down syndrome are up to 100 times more likely to develop leukemia.
Children with Down's syndrome often learn to speak later than other children and have mental and intellectual disabilities. While some people with Down syndrome are severely mentally impaired, others are of average intelligence.
People with Down syndrome look different and usually have mental impairments @ Drobot Dean / AdobeStock
Doctors can diagnose trisomy 21 before birth as part of prenatal diagnostics. The doctor extracts amniotic fluid from the pregnant woman.
The cells from the amniotic fluid are examined by experts in a chromosome analysis. The diagnosis can also be made using the molecular biological method of polymerase chain reaction (PCR).
Ultrasound also shows signs that indicate Down's syndrome:
After birth, a chromosome analysis of the child's blood cells can provide certainty and confirm the diagnosis.
A causal treatment is not possible, the therapy depends on the symptoms that occur.
Early individual support increases the chances of a normal and independent life for affected children.
If there are other health problems, those affected receive medication. Surgical interventions are possible for heart defects or pronounced anomalies in the digestive tract.
The physical and mental impairments that occur with Down syndrome vary greatly. Some people with Down syndrome live independently, have their own home and are able to work. Others, however, are permanently dependent on care and support.
The average life expectancy is lower, as people with Down syndrome age prematurely and have an increased risk of leukemia. Sudden cardiac death is also more common. On average, people with trisomy 21 live to be between 50 and 60 years old.
