Down syndrome is a genetic disorder caused by the presence of an extra copy of the 21st chromosome, instead of the usual two copies.  This extra chromosome leads to issues that affect both the cognitive and physical ability of an individual.  Although the cognitive abilities will vary, most have mild to moderate cognitive issues as well as some delay in development.

There are three types of Down syndrome:

  • Trisomy 21 – the most type of Down syndrome, occurs when there are three copies of chromosome number 21.  Trisomy 21 accounts for 95% of all cases of Down syndrome.
  • Translocation – occurs when the 21stchromosome breaks off during the cell division and attaches to another chromosome (usually chromosome number 14).  Translocation accounts for approximately 4% of all cases of Down syndrome.
  • Mosaicism – occurs when the nondisjunction of the 21stchromosome takes place in one of the initial cell divisions after fertilization.  Mosaicism accounts for approximately 1% of all cases of Down syndrome.

Down syndrome is the most frequently occurring chromosomal congenital anomaly in Canada.  In Canada, approximately 1 in every 781 babies is born with Down syndrome. There are an estimated 45,000 Canadians with Down syndrome.

Down syndrome occurs in people of all races and economic levels. The risk of having a baby with Down syndrome increases with the age of the mother.  Although the risk is higher among older mothers, more than half of the babies with Down syndrome born in Canada, are born to a mother under 35 years of age.  This is due to the higher fertility rates in younger women.

With the advancements in health care, the life expectancy for people with Down syndrome has increased dramatically in recent decades – from a life expectancy of 25 years of age in 1983 to 60 years of age today.  People with Down syndrome have an increased risk for certain medical conditions which may include:

  • congenital heart defects,
  • gastrointestinal issues
  • sleep issues
  • respiratory infections
  • vision and hearing problems,
  • thyroid conditions
  • increased risk of obtaining childhood leukemia

Many of these conditions are now treatable, and many people with Down syndrome lead healthy lives.

Many people with Down syndrome may share the following similar physical features:

  • low muscle tone
  • small stature
  • an upward slant to the eyes
  • a single deep crease across the center of the palm

Every person with Down syndrome is a unique individual and may possess these characteristics to different degrees or not at all.  They will most likely resemble other members of their families.

All people with Down syndrome experience cognitive delays, but the effect is usually mild to moderate and is not indicative of the many strengths and talents that each individual possesses.

People with Down syndrome attend school, work, participate in decisions that affect them, have meaningful relationships, vote and contribute to society in many wonderful ways.

Quality educational programs, a stimulating home environment, good health care and positive support from family, friends and the community enable people with Down syndrome to lead fulfilling and productive lives.

Tips for talking about people with Down syndrome:

  • Use people-first language.  People with Down syndrome are people first and should always be addressed that way.
  • Down syndrome doesn’t define people.  Do not identify them by their disability first.
  • Down syndrome is a condition not a disease.  People “have” Down syndrome ~ they do not “suffer from” it and are not “afflicted by” it.
  • The use of the word “retarded” in any derogatory context is hurtful and suggests that people with disabilities are not competent.

Down vs. Down’s

DSAT uses the preferred spelling, Down syndrome, rather than Down’s syndrome.

Down syndrome is named for the English physician John Langdon Down, who characterized the condition, but did not have it. An “apostrophe s” connotes ownership or possession.

Do Say

child with Down Syndrome

typically developing or typical

intellectual disability or cognitive disability

Don’t Say

Down syndrome child or Down’s child or Down’s (i.e. he has Down’s)


Mental retardation or retarded