Book T of C
Chap T of C
This is the 2007 version. Click here for the 2017 chapter 12 table of contents.
Down Syndrome is the most common form of mental retardation. It is caused by a common genetic problem that can be diagnosed while a baby is still in the womb.
What is Down Syndrome? What are some physical symptoms of Down Syndrome?
Physical symptoms of Down Syndrome children may include the following:
—short, wide, or broad body parts: e.g. a short thick neck; a large tongue which may protrude involuntarily; small, broad, flat hands and feet; lack of overall body height
—a distinctive facial appearance, including small teeth; underdeveloped bones of the nose; small, round, bulging or slanted-looking eyes with a fold of skin near the bridge of the nose
—a variety of medical problems, not inevitable, but more common among Down Syndrome children: heart disorders, eye problems, a rare type of leukemia, missing or misaligned teeth, and metabolic irregularities
Why is it not in DSM-IV?
Down Syndrome is not explicitly addressed in DSM-IV, except for a passing mention during the discussion of how to rate different degrees of mental retardation on Axis 2. The reason it is left out of the manual, presumably, is that Down Syndrome is a genetic disorder, and if DSM-IV were to include every genetic disorder, it would probably triple in size.
What does it mean to say "trisomy of chromosome 21"?
Down Syndrome is caused by failure of the two chromosomes in pair 21 to separate during meiosis or separation of chromosomes in the developing human ovum or egg. The Down Syndrome child ends up with 47 chromosomes instead of 46, because there are three chromosomes where there should be two. That is the meaning of the word trisomy—literally three-ism—when people describe the genetic basis of Down Syndrome as trisomy of chromosome 21.
Where did the term "mongolism" come from?
Down Syndrome is named after Langdon Down, who described it in 1866. He believed it was an "evolutionary throwback to the Mongol race" and for years the term mongolism was used to describe the syndrome. That term, like so many labels in this field (even mental retardation) has fallen out of use. You will never see references to mongoloids in modern literature, unless it is to criticize the old use of the term. Authors seem undecided, however, about whether to put the apostrophe and "s" after Down. The syndrome is called both Down Syndrome and Down's Syndrome.
Research suggests there may be a link between Down Syndrome and Alzheimer's Syndrome, a disease that causes mental deterioration in old age. About 80% of people with Down Syndrome live past the age of 50, but many of them show Alzheimer's-like symptoms in their 40s. Alzheimer's Syndrome is based partly on genetic inheritance, so there may well be an overlap in the genes or body systems affected by the two disorders.
What is the reputation of Down Syndrome children?
Down Syndrome children have a reputation for being affectionate and sweet natured.
A visitor of an institution summarized her observations: "As playmates, they are always hugging and kissing one another with vague but genuine smiles of affection. They come up and put their arms around the stranger as confidently as a puppy jumping up on a visitor, and though not understanding a word said to them, good-naturedly answer yes to any question, hoping that will please." (Benda, 1946, p.61, cited in Robinson & Robinson, 1965)
Parents sometimes resent the patronizing tone of such observations. They point out that cute children grow into adults who may present difficult medical and psychological problems. It is true, however, that most people with Down Syndrome are very sociable and loving as children.
What is Lesch-Nyhan syndrome and what point does it illustrate here?
Down Syndrome dominates public discussions of "special children" because it is the most common mental retardation syndrome. It affects about 1 in 800 children. But there are hundreds, perhaps thousands, of less common syndromes, each with its own unique characteristics. For example, Lesch-Nyhan Syndrome, afflicts 1 in 50,000 boys. It is rare, but for those whom it affects, it is an all-consuming problem. Victims of Lesch-Nyhan Syndrome mutilate themselves if given a chance. If restrained, they appear happy; if released, they cry, bite themselves, and strike out at objects and people. Most die before adulthood. Many other genetic disorders produce equally unique and distinctive symptoms.
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