Down Syndrome

A child with Down syndrome

Down syndrome (also known as Down's syndrome) encompasses a number of genetic disorders, of which trisomy 21 (a nondisjunction) is the most representative, causing highly variable degrees of learning difficulties as well as physical disabilities. It is named for John Langdon Down, the British doctor who first described it in the late 19th century.

Overview

Down syndrome is a syndrome that causes slowed growth, abnormal facial features, and mental retardation. It is caused by an extra chromosome 21. Incidence of Down syndrome is estimated at 1 per 800 births, making it the most common chromosomal abnormality. The maternal age effect influences the risk of conceiving a baby with the syndrome. At age 20 to 24, it is 1/1490, while at age 40 it is 1/106, and at age 49 is 1/11. (Hook EB., 1981). Genetic counseling and genetic testing such as amniocentesis are usually offered to families who may be at increased risk of having a child with Down syndrome. Many children with Down syndrome are born to women under the age of 35 because routine testing is not usually offered to such women. Women over 35 are often given an amniocentisis and 9 out of 10 choose to abort the affected fetus.

The term 'Down's syndrome' was first used in 1961 by the editor of The Lancet 2. It was originally called mongolism or mongolian idiocy, after a perceived resemblance observed by Down between the faces of some of his patients with Down syndrome and the Mongoloid race. This usage is now viewed by medical professionals as offensive and medically meaningless, and is not commonly used today.

While most children with Down syndrome have a lower than average cognitive function, some have earned college degrees with accommodations, and nearly all will learn to read, write and do simple math. The clinical features of Down syndrome include any of a number of features that also appear in people with a standard set of chromosomes. They include a "simian crease" - a single crease across one or both palms, almond shaped eyes, shorter limbs, heart and/or gastroesophageal defects, speech impairment, and perhaps a higher than average risk of incidence of Hirschsprung's disease. Young children with Down syndrome are also more prone to recurrent ear infections and obstructive sleep apnea.

Early educational intervention, screening for common problems such as thyroid functioning, medical treatment where indicated, a conducive family environment, vocational training, etc., can improve the overall development of children with Down syndrome. On the one hand, Down syndrome shows that some genetic limitations can not be overcome; on the other, it shows that education can produce excellent progress whatever the starting point. The commitment of parents, teachers and therapists, to individual children, has produced previously unexpected positive results.

Medical research

Of the inborn disorders that affect intellectual capacity, Down syndrome is the most prevalent and best studied. Down syndrome is a term used to encompass a number of genetic disorders of which trisomy 21 is the most frequent (95% of cases). Discovered by the Parisian physician Jerome Lejeune in 1959, Trisomy 21 is the existence of the third copy of the chromosome 21 in cells throughout the body of the affected person. Other Down syndrome disorders are based on the duplication of the same subset of genes (e.g., various translocations of chromosome 21). Depending on the actual etiology, the degree of impairment may range from mild to severe. In rare cases trisomy 21 is present in some cell lines but not all, due to an anomalous early cell division in the zygote. There is evidence that this variant, called mosaic Down syndrome, may produce less developmental delay, on average, than full trisomy 21. 3

Trisomy 21 results in over-expression of genes located on chromosome 21. One of these is the superoxide dismutase gene. Some (but not all) studies have shown that the activity of the superoxide dismutase enzyme (SOD) is elevated in Down syndrome. SOD converts oxygen radicals to hydrogen peroxide and water. Oxygen radicals produced in cells can be damaging to cellular structures, hence the important role of SOD. However, the hypothesis says that once SOD activity increases disproportionately to enzymes responsible for removal of hydrogen peroxide (e.g., glutathione peroxidase), the cells will suffer from a peroxide damage. Some scientists believe that the treatment of Down syndrome neurons with free radical scavengers can substantially prevent neuronal degeneration. Oxidative damage to neurons results in rapid brain aging similar to that of Alzheimer's disease.

Another chromosome 21 gene that might predispose Down syndrome individuals to develop Alzheimer's pathology is the gene that encodes the precursor of the amyloid protein. Neurofibrillary tangles and amyloid plaques are commonly found in both Down syndrome and Alzheimer's individuals. Layer II of the entorhinal cortex and the subiculum, both critical for memory consolidation, are among the first affected by the damage. A gradual decrease in the number of nerve cells throughout the cortex follows. A few years ago, Johns Hopkins scientists created a genetically engineered mouse called Ts65Dn (segmental trisomy 16 mouse) as an excellent model for studying the Down syndrome. Ts65Dn mouse has genes on chromosomes 16 that are very similar to the human chromosome 21 genes. With this animal model, the exact causes of Down syndrome neurological symptoms may soon be elucidated. Naturally, Ts65Dn research is also likely to highly benefit Alzheimer's research.

While there are a number of commercially promoted dietary supplements on the market, especially in the USA, mainly involving various combinations of vitamins and minerals, none of these have been medically approved for use in the UK for the mass treatment of people with Down syndrome and none appear to lead to any proven lasting benefits. All remain highly controversial.

Down syndrome's sociology

Advocates for people with Down syndrome stress that affected individuals have the same human rights and emotions as any other human beings. The abuse and forcible institutionalization of people with Down syndrome was closely linked to early twentieth-century racial and eugenic theory, culminating in the killing of many people with Down syndrome and other disabilities by the Nazi government in Germany in the 1930s-1945, and the creation of compulsory sterilization programs around the world which targeted the mentally disabled.

Today, Down syndrome is considered grounds for abortion in an increasing number of countries. The number of children born with Down syndrome is decreasing due to the large number of abortions following an early diagnosis of Down syndrome during pregnancy. In a hearing before the German Parliament, doctors stated that 90% of all fetuses prenatally diagnosed with Down syndrome are aborted. This number is consistent with the official statistics, wherein 1500 children with Down Syndrome should, statistically, have been born per year (at a prevalence rate of 1:600), but only 63 per annum were listed in the 1995 birth register.

Advocates for people with Down syndrome also point to various factors, such as special education and parental support groups, that make life easier for parents of children with the disorder.

In most developed countries, since the early 20th century many people with Down syndrome were housed in "mental subnormality" institutions or colonies and excluded from society. However, nowadays parents, educators and other professionals generally advocate a policy of "inclusion", bringing people with any form of mental or physical disability into general society as much as possible. In some countries, people with Down syndrome are educated in the normal school system, if practical.

Despite this change, the reduced abilities of people with Down syndrome pose a challenge to their parents and families. While living with their parents is preferable to institutionalization for most adults with Down syndrome, they often encounter patronising attitudes and discrimination in the wider community.

Although some people with Down syndrome are able to run their own household, apply for a regular job, get a driver's licence and take care of insurances, etc, by themselves, most need some degree of assistance. Whilst preferable to institutional living, the 1980's and 1990's experiments with group homes were not especially successful, and a number of new models are emerging. In the past few years the independent (supported) living model has found favour with UK governments. With Direct Payments, some people are able to employ their own staff. Individuals can take on their own tenancy, and receive support from a skilled caregiver in organizing their own life, studies, career, and outside interests.

Many children with Down syndrome in the UK are now educated in mainstream schools, learn to read and write, and are likely to live productive and valued lives as part of their families and communities. However, full-time mainstreaming proves difficult after the first few years of schooling, because the intellectual gap between children with and without Down syndrome widens at this age. Complex thinking as required in sciences but also in history, the arts, and other subjects is often beyond their abilities, or achieved much later than in most children. Therefore, if they are to benefit from mainstreaming without feeling inferior most of the time, special adjustments must be made to the curriculum.

Another issue is the danger of underestimating their abilities. This was more common in institutions, where Down Syndrome children often failed to reach their potential despite being capable of much more, but this issue is often present in school as well. For example, a recent study successfully taught 3 year olds with Down Syndrome, who would be developmentally at an 18 month old level, to read, and found their speech development was accelerated. A few people have even suggested that children with Down Syndrome may have normal intellectual potential, but are greatly underestimated.

Some European countries such as Germany and Denmark advise a two-teacher system, whereby the second teacher takes over a group of disabled children within the class. A popular alternative is cooperation between special education schools and mainstream schools. In cooperation, the core subjects are taught in separate classes, which neither slows down the non-disabled students nor neglects the disabled ones. Social activities, outings, and many sports and arts activities are performed together, as are all breaks and meals.

Individuals with Down syndrome share many of the characteristics of their parents, with an average life expectancy of 49 years in the USA versus 77 years for the whole population, having increased from 25 years 4. This increase is credited mainly to improved diet, housing, and health and social care. Many children and adults with Down syndrome enjoy a satisfactory quality of life, and the extra chromosome may even confer some health benefits, such as reduced incidence of certain cancers caused by double immunity. Lung cancer, for instance, is virtually unknown in people with Down syndrome. Conversely, leukemia is more common than in the general population.

Men with Down syndrome are usually infertile, but some women with Down syndrome have had children. A woman with Down syndrome could pass Down syndrome to her children.

Notable individuals

Notable people with Down syndrome include:

• Stephane Ginnsz, actor (Duo) First actor with Down syndrome in the lead part of a motion picture. Duo won both the Martin Scorsese and the Warner Bros. Pictures Film Awards, was an official entry at the 23rd Student Academy Awards, Finalist at the 1996 Chicago International Children's Film Festival, Winner of the 1996 Wasserman Award for best cinematography and nominated for a TASH Film Award. For more info, please visit the official Duo film site and Stephane's official site.
• Chris Burke, actor (Life Goes On) and autobiographer
• Andrea Friedman, actor (Life Goes On), guest appearances on many other shows
• Pascal Duquenne, actor (Le Huitième Jour aka The Eighth Day, Toto le héros aka Toto the Hero)
• Anne de Gaulle (1928-1948), daughter of Charles de Gaulle
• Miguel Tomasin, singer with Argentinian avant-rock band Reynols

Down syndrome in fiction

• Bret Lott: "Jewel"
• Morris West: "The Clowns of God"
• Bernice Rubens: A Solitary Grief
• Emily Perl Kingsley: "Welcome to Holland"
• The Kingdom and its American counterpart, Kingdom Hospital
• Elizabeth Laird: Red Sky in the Morning
• Stephen King: "Dreamcatcher"
• Dean Koontz: "The Bad Place"
• Alex Ginnsz: "Duo"
• Flannery O'Connor: The Violent Bear It Away

Sources

• Hook EB. Rates of chromosomal abnormalities at different maternal ages. Obstet Gynecol 1981;58:282.
• 2:www.intellectualdisability.info/values/history_DS.htm
• 3:www.ds-health.com/mosaic.htm
• 4:www.newscientist.com/news/news.jsp?id=ns99992073

Further reading

• Down Syndrome: The Facts. (1997), Selikowitz, M.(2nd ed.). Oxford, UK; New York, NY, USA: Oxford University Press.
• Down Syndrome: A Promising Future, Together. (1999), Hassold, T. J. and Patterson, D. (Eds.). New York, NY, USA: Wiley Liss.
• Count us in - Growing up with Down syndrome. (1994) Kingsley, J. and Levitz, M. (1994) San Diego, CA, USA: Harcourt Brace.
• Medical and Surgical Care for Children with Down Syndrome: A Guide for Parents. (1995) Van Dyke, D. C., Mattheis, P. J., Schoon Eberly, S., and Williams, J. Bethesda, MD, USA: Woodbine House.
• Adolescents with Down Syndrome: Toward a More Fulfilling Life. (1997) Pueschel, S. M. and Sustrova M. (Eds.) Baltimore, MA, USA: Paul H. Brookes Pub.
• Living with Down syndrome (2000), Buckley, S. Portsmouth, UK: The Down Syndrome Educational Trust. Also available online: http://www.down-syndrome.info/library/dsii/01/01/

External links

• AllDownSyndrome.com
• The Official Site of the Film Duo, starring Stephane Ginnsz
• Stephane Ginnsz, Actor with Down Syndrome - Official Website
• Key facts about Down syndrome
• Living with Down syndrome (Online book)
• Down Syndrome Information web site
• National Down Syndrome Society web site
• National Down Syndrome Congress web site
• Down Syndrome: For New Parents
• The Down Syndrome Educational Trust web site
• Down Syndrome Research Foundation web site
• UK Down's Syndrome Association web site
• Information on the original description of Down syndrome
• Down Syndrome
• Down Syndrome testing in UK
• Down Syndrome child learning with laptops