The most common chromosomal disorder in humans, Down syndrome occurs in 1 out of 1000 births. There are typically 23 pairs of chromosomes in human cells when there is a presence of partial or an entire extra chromosome number 21, it leads to Down syndrome. Common among older women with delayed pregnancy, Down syndrome can occur in people of all races and socio-economic groups.
Some Common Symptoms of Down Syndrome-
- Atypical faces
- Delayed milestones
- Subnormal intelligence
- Delayed speech
- Variable hearing loss
- Joint laxity
- Short Stature
Some Rare Symptoms of Down Syndrome-
A child may also have problems associated with – eyes, heart, blood, and bones. Besides, he/she may have a higher risk of developing dementia and cancer.
This condition can easily be diagnosed by screening the pregnancies through ultrasounds and blood tests. Thus, terminating the pregnancy in time. After birth, the child’s facial features help in suspecting the diagnosis, which can be confirmed by a genetic blood test called karyotyping.
Interventions That Can Improve Child’s Quality of Life-
- Early childhood rehabilitation
- Screening for commonly associated problems
- Medical treatment when indicated
- Familial support
- Occupational therapy
Then there are specially crafted programs that involve trained therapists and educators whose aim is to help the child with Down syndrome develop social, motor, language, and self-help skills
Possible Genetic Causes of Down Syndrome.
- Most often, the cause of Down syndrome is an extra chromosome 21 in all cells of the affected person.
- In these cases, the chromosome 21 pair fails to separate during the formation of an egg (or sperm); this is called “nondisjunction.”
- When the egg with 2 copies of chromosome 21, unites with a normal sperm with one copy of chromosome 21 to form an embryo, the resulting embryo has 3 copies of chromosome 21 instead of the normal two.
- The extra chromosome is then copied in every cell of the baby’s body, causing the features of Down syndrome.
Mosaic trisomy 21.
- In mosaic trisomy 21, only some of the cells in a person’s body have an extra chromosome 21.
- In this situation, the fertilized egg may have the right number of chromosomes, but due to a cell division error early in the development of the embryo, some cells “acquire” an extra chromosome 21.
- A person with mosaic trisomy 21 typically has 46 chromosomes in some cells and 47 chromosomes (with the extra chromosome 21) in others.
Translocation trisomy 21.
- About 3-4% of people with Down syndrome have cells that contain 46 chromosomes. However, there is an extra a chromosome 21 material that gets translocated onto another chromosome.
- For parents of a child with Down syndrome due to a translocation, there may be an increased chance of Down syndrome in future pregnancies.
- This is because one of the two parents may be a carrier of a balanced translocation. However, not all parents of people with translocation trisomy 21 have a translocation.
According to a recent survey, about 10% of the children with Down syndrome attend regular schools. Their life-expectancy has also improved. However, frequent infections and heart problem are still the major concerns to look for.
Written by: Dr. H. Kaur
Edited by: S. Ray