What is Down syndrome?
Down syndrome, also known as Trisomy 21, is a genetic disorder in which the baby is born with an extra copy of chromosome 21. This condition is one of the leading causes of cognitive impairment. Every child born with this condition is different. Almost all the people with Down syndrome are found to have intellectual disabilities, as well as physical problems. Some other health problems may also be seen in people with Down syndrome. Most of the babies with Down syndrome are born with heart disease. Some of them have dementia. Some of these patients have problems with eyes, thyroid, skeleton, and intestines. Hearing problems are also associated with this congenital disorder.
Chromosomes in Down syndrome an overview
As stated earlier, an extra copy of chromosome 21 is responsible for the whole condition. Normally, a person has 46 chromosomes, 23 from mother and 23 from father. But in this condition, the baby inherits one extra chromosome from one of the parents. Mostly, the extra copy of chromosome 21 comes from the mother.
Sometimes, the person with Down syndrome does not have an extra copy. He rather inherits extra chromosome 21 genes. This is very rare but possible. This condition of inheriting extra genes is called translocation.
On the other hand, in some cases, baby inherits additional genes from chromosome 21 but not in every cell of the body. Such condition is referred as mosaic Down syndrome. Such individuals have all the symptoms similar to that of a person with Down syndrome.
Risk factors for conceiving a child with Down syndrome
Advanced maternal age is the only risk factor for conceiving a child with Down syndrome. The greater the age of mother, the greater is the risk of a child with Down syndrome. Age above 40 is considered risky. If a mother has a child with Down syndrome, there are greater chances of having the next baby with Down syndrome.
Symptoms of Down syndrome
Although the symptoms of Down syndrome vary from person to person, most patients with Down syndrome have physical characteristics that are recognizable.
- The most common and recognizable symptom seen in individuals with Down syndrome is a flattened face and nose. Their neck is shorter than normal. They have small mouth, small ears, and a large protruding tongue.
- Brushfield spots (little white spots) on the iris (colored part of the eye) are seen in most of the cases.
- All the individuals with Down syndrome have delayed growth and development. They don't reach the average height; neither do they reach the developmental milestones. They are usually weak and have poor muscle tone.
Delayed cognitive impairment
This is the most common condition associated with Down syndrome. Cognitive development of the affected child is delayed and they have difficulty in learning. The brain size of such individuals is smaller than the normal individuals.
Down syndrome also involves other systems and causes problems such as:
- Cardiac problems
- Gastrointestinal tract disorders
- Sleep apnea
- Frequent infections
- Infantile spasms
- Visual impairment
- Obsessive compulsive disorder
Prenatal screening tests
Prenatal screening options are offered to the parents who think they are at the risk of conceiving a child with Down syndrome. Screening tests include:
- Alpha-fetoprotein screening being most widely used
- Nuchal translucency test
Diagnosis of Down syndrome
Latest technology has made it possible to diagnose Down syndrome before birth.
- Amniocentesis: It is performed between 16 and 20 week of gestation (pregnancy).
- Chorionic villus sampling: Performed between 11 and 12 weeks of pregnancy.
Warning: There is a very little risk of miscarriage while performing these tests. However, most of the mothers, who had these tests, had a normal vaginal delivery without any early or late complications.
Diagnosis after birth: If a child is born with symptoms of Down syndrome, the diagnosis can be confirmed with the help of chromosomal analysis.
What is the treatment of Down syndrome?
No doubt, genetic cause of Down syndrome is known; there is no cure of this disease yet. The treatment given to the patients with Down syndrome is symptomatic. Surgeries are performed if the disease is showing severe symptoms such as cardiac abnormalities or gastrointestinal tract irregularities.