Down syndrome poses mental and physical challenges for the affected individual. Although individuals with this condition may look or act similarly, each has different abilities. A person with Down syndrome generally has an intelligence quotient, which is a measure of intelligence, in the mild-to-moderate low range. Children with this condition are slower to speak than other children. 

There are four common types of signs and symptoms in Down syndrome that include:

  1. Physical features: Common physical features include:
    1. Flattened face, especially the bridge of the nose
    2. Almond-shaped eyes with an upward slant
    3. Short neck
    4. Small and low-set ears
    5. A protruding tongue that sticks out of the mouth
    6. Small hands and feet
    7. Single palmar crease (line across the palm)
    8. Broad and short hands with small pinky fingers that may curve toward the thumb
    9. Poor muscle tone
    10. Loose joints
    11. Shorter stature for their age
    12. Tiny white spots on the iris (colored part of the eye)
    13. Abnormal breastbone
  2. Delayed motor skills: Children with Down syndrome reach milestones such as crawling and walking at a later age than other children. They may have problems with feeding, brushing their teeth, getting dressed, and using the toilet.
  3. Intellectual disabilities: Most children with Down syndrome have mild to moderate intellectual disabilities. Speech and language development is typically delayed. Cognitive skills, such as memory, thinking, and reasoning, may be affected. Cognitive decline may be associated with early-onset (in the 50s or 60s) Alzheimer’s disease in people with Down syndrome.
  4. Associated conditions: People with Down syndrome may develop other health conditions such as
    1. Frequent infections, especially respiratory and ear infections
    2. Breathing problems
    3. Thyroid diseases
    4. Leukemia
    5. Heart defects
    6. Seizures
    7. Hearing loss
    8. Eye diseases
    9. Gut problems (such as gastroesophageal reflux disease, celiac disease, esophageal atresia, and intestinal obstruction)
    10. Autoimmune conditions (such as autoimmune thyroid disease)
    11. Accelerated aging

Each person with Down syndrome, however, is unique and may have these characteristics to varying extents or not at all.

What is Down syndrome?

Down syndrome is caused by the presence of an extra chromosome.
Down syndrome is caused by the presence of an extra chromosome.

Down syndrome is a type of genetic disorder in which a person has an extra chromosome (rod-like structures that contain genes) inside the cells. The syndrome is named after the English physician John Langdon Down who provided the first accurate description of this condition. Down syndrome is the most common chromosomal condition affecting approximately one in every 700 babies born in the United States. Around 6,000 babies are born with Down syndrome each year in the United States.

Causes and three types of Down syndrome

Down syndrome is a genetic condition. Despite being a genetic condition, however, Down syndrome is generally not inherited

Most cases (about 95%) of Down syndrome are caused by trisomy 21, a condition in which cells of the affected person carry three copies of chromosome 21 instead of the normal 2. 

Each cell in the human body has a nucleus in which genes are arranged in rod-like structures called chromosomes. They can be described as small “packages” of genes in the body. They control inherited traits such as how a baby develops inside the womb and how its body functions in the womb and after birth. 

Normally, each cell contains 46 chromosomes arranged in 23 pairs. A baby with Down syndrome, however, has an extra copy of chromosome 21. This condition of having three copies instead of two is called trisomy, or trisomy 21. The presence of an extra copy of chromosome 21 causes changes in how the baby’s body and brain develop and can lead to physical and mental abnormalities. 

Besides trisomy 21, two other genetic abnormalities called mosaic Down syndrome and translocation Down syndrome, can also cause Down syndrome: 

  • Mosaic Down syndrome: Only some cells have trisomy 21, whereas other cells are normal. It is a rare type of Down syndrome. 
  • Translocation Down syndrome: Involves the transfer of a portion of chromosome 21 to another chromosome.

What are risk factors for Down syndrome?

One of the most important risk factors for Down syndrome is advanced maternal age (over 35). However, because younger women are more likely to have babies, most babies with Down syndrome are born to women under age 35.

Having a child with Down syndrome can also increase your risk of having another child with Down syndrome, although it is not definite.

Translocation Down syndrome may be inherited from a parent, meaning that if the mother or father are carriers of this condition, they may pass it on to their baby. However, even translocation Down syndrome is not always inherited.

What is the treatment for Down syndrome?

Treatment of Down syndrome involves various specialists to manage the emotional, cognitive, physical, and behavioral challenges associated with this condition. Because each child is affected differently, treatment is tailored to each child to suit their specific needs.

Treatment generally involves the following:

  • Behavioral therapy to manage temper or emotional issues
  • Physical therapy to keep bones, muscles, and joints healthy
  • Medications to manage conditions such as infections or thyroid diseases
  • Surgery to treat conditions such as heart defects or intestinal obstruction
  • Speech therapy to help with speech development
  • Occupational therapy to help them lead a reasonably independent life

Is Down syndrome curable?

Down syndrome is not curable. It is a lifelong condition. Supportive therapy early in life can often help babies and children with Down syndrome to improve their physical and mental abilities. Early screening of babies with Down syndrome can also help in managing associated conditions such as heart defects and hearing problems. Supportive therapy helps children with Down syndrome develop to their full potential. The therapy includes speech, occupational and physical therapy besides extra help and support in school. 

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Medically Reviewed on 6/21/2022
References
https://www.ndss.org/about-down-syndrome/down-syndrome

https://www.nichd.nih.gov/health/topics/downsyndrome

https://www.cdc.gov/ncbddd/birthdefects/downsyndrome.html

https://www.uptodate.com/contents/down-syndrome-clinical-features-and-diagnosis