A second whole or partial copy of chromosome 21 is produced as a result of faulty cell division, which results in the genetic condition known as Down syndrome. Down syndrome’s physical characteristics and developmental abnormalities are brought on by this excess genetic material.
Individuals with down syndrome may have varying degrees of intellectual disability and developmental delays. It is the most prevalent genetic chromosomal defect and the root of children’s learning problems. It frequently results in other medical issues as well, such as cardiac and gastrointestinal problems.
The quality of life for children and adults with Down syndrome can be significantly improved, and early interventions can help them lead fulfilling lives.
Symptoms
Individuals with Down syndrome might have mild, moderate, or severe intellectual and developmental issues. While some people have substantial health issues, including serious heart defects, others are in generally good health.
Both Down syndrome children and adults have distinctive face characteristics. Although not all individuals with Down syndrome share the same characteristics, some of the more typical ones are as follows:
- Face that is sunk in
- Little head
- Brief neck
- Erupting tongue
- Eyelids that slant upward (palpebral fissures)
- Tiny or unusually shaped ears
- Muscle tone issues
- Hands that are small and broad with just one wrinkle in the palm
- Fingers that are relatively short and little hands and feet
- Too much flexibility
- Brushfield’s spots are minuscule white dots on the iris, the coloured portion of the eye.
- Brief height
Although Down syndrome babies may be of ordinary size, they often grow slowly and stay smaller than children of the same age.
Causes
There are typically 23 pairs of chromosomes in human cells. Each pair of chromosomes contains one from your mother and one from your father.
Chromosome 21-related faulty cell division causes Down syndrome. These errors in cell division lead to an additional whole or partial copy of chromosome 21. The distinctive traits and developmental issues of Down syndrome are brought on by this additional genetic material. Down syndrome can result from any one of three genetic variations:
21 trisomy. Trisomy 21 (having three copies of chromosome 21 instead of the normal two copies in all cells) accounts for about 95% of cases of Down syndrome. This results from sperm or egg cell development that results in aberrant cell division.
Down syndrome mosaic. A person with this uncommon type of Down syndrome only has a few cells with an extra copy of chromosome 21. After fertilisation, aberrant cell division results in a mosaic of normal and abnormal cells.
Translocation the Down syndrome. Additionally, down syndrome can develop before or during conception if a piece of chromosome 21 translocates (attaches to another chromosome). These kids have two copies of chromosome 21 as usual, but they also contain additional chromosome 21 genetic material linked to another chromosome.
Down syndrome is not known to be brought on by environmental or behavioural causes.
Is it hereditary?
Down syndrome is frequently not inherited. It results from an error in cell division during the foetus’ early development.
Translocation From a parent to a child, down syndrome can be transmitted. Only a small percentage of children with Down syndrome—roughly 3–4 percent—have translocation, and some of them acquired it from one of their parents.
When balanced translocations are inherited, the mother or father does not have any additional genetic material but does have some altered genetic material from chromosome 21 on another chromosome. This indicates that although the person does not exhibit any indications or symptoms of Down syndrome, they are capable of passing on an imbalanced translocation to their offspring, who would then develop the condition.
Risk elements
Some parents are more likely to give birth to a child who has Down syndrome. Risk elements consist of:
Raising the maternal age. The likelihood that a mother may give birth to a child with Down syndrome rises with age because older eggs are more likely to undergo an incorrect chromosomal division. After age 35, a woman’s chance of having a child with Down syndrome rises. However, because younger women give birth to more kids, the majority of children with Down syndrome are born to mothers under the age of 35.
Being genetic translocation carriers for Down syndrome. The genetic translocation for Down syndrome can be passed on to offspring by both sexes.
I have a child who is Down syndrome. A child with Down syndrome is more likely to be born to parents who already have one and to parents who themselves have a translocation. Parents can analyse the possibility of having a second child with Down syndrome with the aid of a genetic counsellor.
Prevention
The Down syndrome cannot be avoided. A genetic counsellor should be consulted before becoming pregnant if you are highly likely to have a child with Down syndrome or if you currently have a kid who has the condition.
You can learn more about your likelihood of becoming pregnant with a Down syndrome child from a genetic counsellor. Additionally, he or she can discuss the different prenatal tests with you and help you weigh their benefits and drawbacks.
