A). Down syndrome is a genetic condition in which a person has an extra copy of chromosome 21, leading to changes in the development of the body and brain. This condition causes mild to moderate intellectual disability, developmental delays, and characteristic physical features. It is also known as trisomy 21 because of the presence of a third copy of chromosome 21.
Definition
Down syndrome occurs when an individual has all or part of an extra chromosome 21. This additional genetic material affects the way the body and brain develop, resulting in physical and intellectual challenges. It usually happens by chance during early fetal development and is not inherited.
Common Symptoms
Physical signs and symptoms of Down syndrome vary but often include:
- Flattened facial features, especially a flat nasal bridge
- Upward slanting eyes with a skin fold on the upper eyelid
- Small head, ears, hands, and feet
- Short neck with excess skin
- Poor muscle tone and loose joints
- A single deep crease across the palm (palmar crease)
- A protruding tongue
- Short stature
- Developmental delays such as late talking and walking
- Intellectual disability typically ranging from mild to moderate
Children with Down syndrome often reach developmental milestones later than other children but can benefit greatly from therapies such as occupational, physical, and speech therapy.