What is Down Syndrome?

Down’s syndrome

Also known as trisomy 21, Down syndrome (or Down’s Syndrome in the UK and many countries) is the most common genetic cause of mild and moderate intellectual disability.

March 21 is celebrated as World Down Syndrome Day. The reason that the date was picked seems obvious to those familiar with the condition. Chromosomes come in pairs. Humans have 46 pairs of chromosomes in the genetic code that tells their bodies how to develop and function. But people with Down syndrome (DS) have a third chromosome on their 21st set of chromosomes. So to celebrate the genetic uniqueness of people with DS, Down Syndrome International has picked March 21st (the 21st day of the third month) as World Down Syndrome Day.

While the most common form of DS involves a genetic condition called trisomy 21, about 10 percent of DS cases are the results of other slightly different genetic conditions. The National Institute of Health has a relatively detailed discussion of the genetics of DS. DS genetics itself is a more technical discussion than can be dealt with here.

A number of physical traits are often observable in DS children at birth. Among them:

  • poor muscle tone
  • a unique facial shape that includes flat facial features and a small nose
  • epicanthic folds on the eyes
  • an almond shape to the eyes
  • abnormal ear shape
  • a large tongue
  • joints that extend beyond the normal range
  • shortened than average limbs
  • a deep crease across the palm of the hand
  • extra space between the big toe and other toes

DS children and adults are at high risk for a number of medical conditions. Heart defects and problems related to the stomach and esophagus are not uncommon. Sleep apnea occurs often in those with Down syndrome. Difficulties in the lower digestive tract (including bowel obstructions) are also common, as are ear infections.

The cognitive functioning of children with DS varies greatly. One of the most controversial issues within the DS communities is the validity of the various tests used by school psychologists to measure cognitive functioning (the term “intelligence” tends to be avoided these days in the context of such tests). Because DS children tend to have reduced verbal skills, many parents and advocates do not feel such tests accurately measure the cognitive abilities of a DS child. That said, some adults with DS have pursued their education to the level of obtaining college degrees (admittedly usually with some level of accommodation for their disability) and the vast majority of DS children will learn to read, write, and perform basic math operations.

DS raises a number of educational issues. There is often a wide gap between the ability DS students have to understand ideas and their ability to express those ideas. Speech therapy is a common part of education for students with DS. Regular occupational therapy is also commonly used to help address delays in both fine and gross motor skills. The most controversial and emotional issue that has to be resolved in the educational environment is the extent to which a DS child is educated with non-disabled peers their own age. DS students usually experience delays in their emotional and social development and these delays lead to a wider and wider gap each year between the social abilities of a DS student and those of their same-aged peers. Whether it is called mainstreaming or inclusion, educating DS students in the general education classroom with their chronological peers has both advantages and disadvantages that must be weighed in each year’s IEP meeting.

The quality of life for people with DS has improved tremendously in the last century. At the start of the Great Depression, the average person with DS lived to be all of nine years old. Today individuals with DS often live into their 50’s. And while life for a DS person a couple of generations ago often involved institutionalization and the isolation and loss of independence that comes with it, today individuals with DS often live happy, relatively independent lives that include marriage and a job. The 1996 film Duo pictured many of the challenges of life with DS today (and featured a leading actor with DS).