What is Down Syndrome?

Down syndrome is the most common form of intellectual disability in the world. It is caused by a genetic abnormality that affects something called a chromosome.

Chromosomes are large structures found in cells that house thousands of genes. People without genetic abnormalities have 23 pairs of chromosomes, and each pair is given a number between 1 and 23.

People with Down syndrome are born with three, rather than two, copies of chromosome 21. Scientists do not know why some babies wind up with the extra chromosome, but they do know that the age of the mother plays a role. As a woman gets older, her risk of having a baby with Down syndrome steadily increases. The father’s age may also be relevant, but scientists do not yet know that definitively.

Common physical signs include:

  • Decreased muscle tone at birth
  • Excess skin at nape of neck
  • Flattened nose
  • Upward slanting eyes
  • Small ears & mouth
  • Wide , short hands with short fingers


Types & Causes of Down Syndrome:

  • Trisomy 21. This is by far the most common type, where every cell in the body has three copies of chromosome 21 instead of two.This is caused by abnormal cell division during the development of the sperm cell or the egg cell.
  • Translocation Down syndrome. In this type, occur when a portion of chromosome 21 becomes attached (translocated) onto another chromosome, before or at conception. These children have the usual two copies of chromosome 21, but they also have additional genetic material from chromosome 21 attached to another chromosome.
  • Mosaic Down syndrome. This is the rarest type, a person has only some cells with an extra copy of chromosome 21. This mosaic of normal and abnormal cells is caused by abnormal cell division after fertilization.


There are two basic types of tests available to detect Down syndrome during pregnancy: screening tests and diagnostic tests.


Complications of Down syndrome include:

  • Heart defects
  • Gastrointestinal (GI) defects
  • Immune disorders
  • Sleep apnea
  • Obesity
  • Spinal problems
  • Leukemia
  • Dementia
  • Endocrine problems
  • Dental problems
  • Seizures
  • Ear infections
  • Hearing and vision problems.


What are common treatments for Down syndrome?

There is no single, standard treatment for Down syndrome. Treatments are based on each individual’s physical and intellectual needs as well as his or her personal strengths and limitations. People with Down syndrome can receive proper care while living at home and in the community.

Early Intervention and Educational Therapy

Treatment Therapies:

  • Physical therapy includes activities and exercises that help build motor skills, increase muscle strength, and improve posture and balance.
  • Speech-language therapy can help children with Down syndrome improve their communication skills and use language more effectively.
  • Occupational therapy helps find ways to adjust everyday tasks and conditions to match a person’s needs and abilities.
  • Emotional and behavioral therapies work to find useful responses to both desirable and undesirable behaviors.

Drugs and Supplements

Some people with Down syndrome take amino acid supplements or drugs that affect their brain activity. However, many of the recent clinical trials of these treatments were poorly controlled and revealed adverse effects from these treatments. Since then, newer psychoactive drugs that are much more specific have been developed. No controlled clinical studies of these medications for Down syndrome have demonstrated their safety and efficacy, however.


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  2. Bull MJ, the Committee on Genetics. Health supervision for children with Down syndrome. Pediatrics. 2011;128:393-406.
  3. Gabbe SG, et al., eds. Genetic screening and prenatal genetic diagnosis. In: Obstetrics: Normal and Problem Pregnancies. 7th ed. Philadelphia, Pa.: Saunders Elsevier; 2017.
  4. Ostermaier KK. Down syndrome: Management. http://www.uptodate.com/home. Accessed Dec. 22, 2016.