Down Syndrome: Causes, Signs, Symptoms, Risk Factors and Treatments

Commonly asked questions about Down syndrome:

What is Down Syndrome?

It is a genetic disorder caused when abnormal cell division results in extra genetic material from chromosome 21. It is the most common genetic chromosomal disorder among children, affecting 1 in every 700 children born.

The condition varies in severity. It causes lifelong intellectual disability and developmental delays, and in some cases, health problems.

What Causes Down Syndrome?

According to the Eunice Kennedy Shriver National Institute of Child Health and Human Development, It is caused by a completely random error in cell division that results in the presence of an extra copy of chromosome 21. This type of cell division error is known as a nondisjunction.

Generally, when one cell divides in two, pairs of chromosomes are split so that each cell gets a copy of that chromosome. However, in nondisjunction, something goes awry and both chromosomes go into one cell, and the second cell does not get a copy of that chromosome.

Oftentimes, the error occurs at random during the formation of an egg or sperm. After extensive research on cell division errors, researchers were able to determine the following:

  • In more than 90% of cases, the extra chromosome 21 comes from the mother in the egg.
  • In only about 4% of cases, the father is the one who provides the extra chromosome.
  • In the remaining cases, the error occurs after fertilization, as the embryo is growing.

What Risk Factors Are Associated With The Development Of Down Syndrome?

There are very few confirmed risk factors associated with this disorder. It occurs all over the world, in people of every race and economic background.

Although a child is capable of being born with it at any maternal age, the key risk factor for a child developing this disease is the age of the mother. According to the National Down syndrome Society, the older a mother is, the higher the risk of her child developing the condition:

  • A mother of 25 years old: there is a 1/1,200 chance that a baby will develop Down syndrome
  • A mother of 35 years old: there is a 1/350 chance
  • A mother of 40 years old: there is a 1/100 chance
  • A mother of 49+ years old: there is a 1/10 chance

Additionally, mothers who have a child born with Down syndrome have a 1 percent chance of having another baby born with the diagnosis as well.

What Are The Signs That A Child May Have Down Syndrome?

The symptoms vary from person to person. In general, there are both physical and mental symptoms that come along with the diagnosis. Physical development is often slower than average, and there are also particular physical traits that are often exhibited. According to the NICHD, these include:

  • Decreased or poor muscle tone
  • Short neck, with excess skin at the back of the neck
  • Flattened facial profile and nose
  • Small head, ears and mouth 
  • Upward slanting eyes, often with a skin fold that comes out from the upper eyelid and covers the inner corner of the eye.
  • White spots on the colored part of the eye
  • Wide, short hands with short fingers
  • A single crease across the palm of your hand
  • A deep groove between the first and second toes

There are several intellectual and developmental symptoms as well, which include:

  • Short attention span
  • Poor judgment
  • Impulsive behavior
  • Slow learning
  • Delayed language and speech development

Is Down Syndrome Curable?

Due to the fact that the condition is the result of a genetic anomaly, there is not a cure at this time.

What Methods Are Used To Help Treat Down Syndrome?

According to Mayo Clinic there isn’t one form of standard treatment. The treatments are based on each individual’s physical and cognitive needs, as well as their own personal strengths and weaknesses. A child that has been diagnosed will most likely receive care from a full team of health professionals to help with his/her specific needs.

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View Sources

  1. Mayo Clinic — What is Down syndrome
  2. Eunice Kennedy Shriver National Institute of Child Health and Human Development — What causes Down syndrome
  3. National Down Syndrome Society — Down syndrome risk factors
  4. Eunice Kennedy Shriver National Institute of Child Health and Human Development — Down syndrome signs 


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Palomaki G, Kloza E, Lambert-Messerlain G, Haddow J, Neveux L, Ehrich M, Van Den Boom D, Bombard A, Deciu C, Grody W, Nelson S, Canick J, DNA sequencing of maternal plasma to detect Down syndrome: An international clinical validation study,  2011, Genetics in Medicine, Vol 13, 913-920