NationMaster - Encyclopedia: Down's syndrome

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A child with Down syndrome

Down syndrome (also called Down's syndrome) encompasses a number of A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. There are a number of possible causes for genetic defects: They may be caused by an unwelcome mutation, as are most cancers. There are genetic disorders caused... genetic disorders, of which A trisomy means the presence of three (instead of the normal two) chromosomes of a particular numbered type in an organism. Thus the presence of three chromosome 21s is called trisomy 21. Most trisomies result in a number of birth defects (which are often present in most individuals with a... trisomy 21 (a In biology, nondisjunction is the failure of a chromosome to split correctly during meiosis. This results in the production of gametes which have either more or less of the usual amount of genetic material, and is a common mechanism for trisomy or monosomy. Nondisjunction can occur in the meiosis I... nondisjunction) is the most representative, causing highly variable degrees of In broad terms, the phrase learning disability covers any of a range of conditions that affect a persons ability to learn new information. These conditions all affect the brain in some fashion. The most common causes are: defects or errors in brain structure lack of communication between various parts... learning difficulties and The term disability, as it is applied to humans, refers to any condition that impedes the completion of daily tasks using traditional methods. National governments and global humanitarian agencies have narrowed this definition for their own purposes, only pledging aid to those with specific disabilities of a certain severity. Types... physical disabilities. It is named for John Langdon-Down, the British doctor who first described it.

Overview

Incidence of Down syndrome is estimated at 1 per 660 births, making it the most common chromosomal abnormality. Maternal age influences the risk of conceiving a baby with the syndrome. At age 20-24, it is only 1/1490, while at age 40 it is 1/106 and at age 49 it is 1/11. (Source: Hook EB. Rates of chromosomal abnormalities at different maternal ages. Obstet Gynecol 1981;58:282.) Genetic counseling generally refers to prenatal counseling done when a genetic condition is suspected in a pregnancy. Genetic counseling can occur before conception (i.e. when one or two of the parents are carriers of a certain trait), during pregnancy (i.e. if an abnormality is noted on an ultrasound... Genetic counseling and Genetic testing allows the genetic diagnosis of vulnerabilities to inherited diseases, and can also be used to determine a persons ancestry. Every person carries two copies of every gene, one inherited from their mother, one inherited from their father. The human genome is believed to contain about 25,000... genetic testing such as Amniocentesis is a medical procedure used for prenatal diagnosis, in which a small amount of amniotic fluid is extracted from the amnion around a developing fetus. It is usually offered when there may be an increased risk for genetic conditions (i.e. Down syndrome, sickle cell disease, cystic fibrosis, etc... amniocentesis are usually offered for families who may be at increased risk to have a child with Down syndrome.

The term was first used by the editor of The Lancet is a British medical journal, published weekly by the Lancet Publishing Group. It takes its name from the surgical instrument called a lancet. The present editor-in-chief is Richard Horton. There are several specialized editions of The Lancet, called The Lancet Neurology, The Lancet Oncology and The... The Lancet in 1961 (As MAD Magazine pointed out on its first cover for the year) was the first upside-down year - i.e., one that looked the same upside down - since 1881, and the last until 6009. Events January January 1 - The farthing coin, used since the 13th century, ceases to be... 1961 [1] (http://www.intellectualdisability.info/values/history_DS.htm). 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 The term Mongoloid describes a proposed race of humans, most of whom live in Asia and the Pacific Rim. The grouping was one of the four major races recognized by Nineteenth Century racial theories. Epicanthal folds and oblique palpable fissures are common among most Mongoloid individuals. Most exhibit Mongolian spot... Mongoloid race. This usage is now viewed as both offensive and medically meaningless.

Children with Down syndrome are at an immediate disadvantage compared with children who do not have DS. The IQ redirects here; for other uses of that term, see IQ (disambiguation). Intelligence quotient or IQ, is a score derived from a set of standardized tests that were developed with the purpose of measuring a persons cognitive abilities (intelligence) in relation to their age group. It is expressed as... IQ of a child with Down syndrome is rarely measured above 60. Brains of children with Down syndrome are usually small and underweight. The Cerebellum (in blue) and cerebral lobes in the human brain General Features Location: It is found at the bottom rear of the head (the hindbrain), directly above the brainstem. Role: The cerebellum is involved in computing movements, directing attention, measuring time, and many other motor and cognitive functions. It is... cerebellum and The brain stem is the stalk of the brain below the cerebral hemispheres. It is the major route for communication between the forebrain and the spinal cord and peripheral nerves. It also controls various functions including respiration, regulation of heart rhythms, and primary aspects of sound localization. Mostly enveloped by... brain stem are unusually small, as is the Superior temporal gyrus of the human brain. The superior temporal gyrus is one of three (sometimes two) gyri in the temporal lobe of the human brain. A gyrus (plural gyri) is a bump or ridge on the surface of the brain. The superior temporal gyrus is bounded by: the lateral... superior temporal gyrus. Educational progress may also be damaged by illness and disabilities, such as recurring In medicine, infectious disease or communicable disease is disease caused by a biological agent (e.g. virus, bacterium or parasite), as opposed to physical (e.g. burns) or chemical (e.g. intoxication) causes. Agents and vectors Infectious disease requires an agent and a mode of transmission (or vector). A good... infectious diseases, heart problems, poor eyesight, and hearing problems. Other physical characteristics associated with the disorder include presence of a A simian crease is a single palmar crease (extending across the palm of the hand), as opposed to three creases people normally have. External links Characteristics, Q&A General info and survey General info In-depth info ... simian crease.

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 we cannot jump over genetic limitations; 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 A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. There are a number of possible causes for genetic defects: They may be caused by an unwelcome mutation, as are most cancers. There are genetic disorders caused... genetic disorders of which A trisomy means the presence of three (instead of the normal two) chromosomes of a particular numbered type in an organism. Thus the presence of three chromosome 21s is called trisomy 21. Most trisomies result in a number of birth defects (which are often present in most individuals with a... trisomy 21 is the most frequent (95% of cases). Trisomy 21 is the existence of the third copy of the This article is about the biological chromosome. For information about chromosomes in genetic algorithms, see Chromosome (genetic algorithm). Figure 1: Chromosome. (1) Chromatid. One of the two identical parts of the chromosome after S phase. (2) Centromere. The point where the two chromatids touch, and where the microtubules attach. (3... 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 This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). Introns are regions often found in eukaryote genes which are removed in the splicing process: only the exons encode the protein. This diagram labels a region of only 40... genes (e.g., various translocations of chromosome 21). Depending on the actual Etiology (alternately aetiology, aitiology) is the study of causation. The term (deriving from the Greek words aitia = cause and logos = word/speech) is used in philosophy, physics and biology in reference to the causes of various phenomena. It is generally the study of why things occur, or even the reasons... etiology, the In broad terms, the phrase learning disability covers any of a range of conditions that affect a persons ability to learn new information. These conditions all affect the brain in some fashion. The most common causes are: defects or errors in brain structure lack of communication between various parts... learning disability may range from mild to severe.

Trisomy 21 results in over- Gene expression (also protein expression or often simply expression) is the process by which a genes information is converted into the structures and functions of a cell. Gene expression is a multi-step process that begins with transcription and translation and is followed by folding, post-translational modification and... expression of genes located on chromosome 21. One of these is the Superoxide dismutase The enzyme superoxide dismutase , or SOD (EC 1.15.1.1), catalyzes the dismutation of superoxide into oxygen and hydrogen peroxide. As such it is an important antioxidant defense in nearly all cells exposed to oxygen. One of the exceedingly rare exceptions is Lactobacillus plantarum and related lactobacilli... superoxide dismutase gene. Some (but not all) studies have shown that the activity of the superoxide dismutase enzyme ( Categories: Construction | Fortification | Stub ... SOD) is elevated in Down syndrome. SOD converts oxygen radicals to The chemical compound hydrogen peroxide (H2O2) is a viscous liquid that has strong oxidizing properties and is therefore a powerful bleaching agent that has found use as a disinfectant and (in high concentrations) as an oxidizer or monopropellant in rockets. Hydrogen peroxide is manufactured commercially by several processes. Inorganic processes... hydrogen peroxide and Drinking water This article focuses on water as we experience it every day. The water (molecule) article describes the water chemical and physical properties from a scientific and technical perspective. Water (from Low German or Old Saxon) is an abundant substance on Earth. It exists in many places and forms... 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 Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = blend) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. Like any catalyst, enzymes work by lowering the activation energy of a reaction, thus allowing the reaction... enzymes responsible for removal of hydrogen peroxide (e.g., Categories: Biochemistry stubs | EC 1.11.1 ... glutathione peroxidase), the cells will suffer from a peroxide damage. Some scientists believe that the treatment of Down syndrome Neurons (also called nerve cells) are the primary cells of the nervous system. In vertebrates, they are found in the brain, the spinal cord and in the nerves and ganglia of the peripheral nervous system. Classes There are three classes of neurons: afferent neurons, efferent neurons, and interneurons. Afferent neurons... neurons with free radical scavengers can substantially prevent neuronal degeneration. Oxidative damage to neurons results in rapid In the anatomy of animals, the brain, or encephalon, is the supervisory center of the nervous system. Although the brain is usually cited as the supervisory center of vertebrate nervous systems, the same term can also be used for the invertebrate central nervous system. In most animals, the brain is... brain aging similar to that of Alzheimers disease (AD) or senile dementia of Alzheimers type is a neurodegenerative disease which results in a loss of mental functions due to the deterioration of brain tissue. Its exact aetiology (cause) is still unknown, but environmental as well as genetic factors are thought to contribute ( mutations in... 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 describes various types of protein aggregations that share specific traits when examined microscopically. The name amyloid comes from the early mistaken identification of the substance as starch (amylum in Latin), based on crude iodine-staining techniques. For a period the scientific community debated whether or not amyloid deposits were... amyloid protein. Neurofibrillary tangles and amyloid plaques are commonly found in both Down syndrome and Alzheimer's individuals. Layer II of the The entorhinal cortext (EC) is an important memory center in the brain. The EC forms the input to the hippocampus and is responsible for the pre-processing of the input signals. In the eyeblink reflex, the association of impulses from the eye and the ear occurs in the entorhinal cortex... entorhinal cortex and the subiculum, both critical for The broad definition of memory consolidation is the process by which recent memories are crystallised into long-term memory. The word consolidation is used to refer to a couple of distinct processes: The molecular process by which long-term conductivity of synapses is affected. Memory consolidation occurs after training or... memory consolidation, are among the first affected by the damage. A gradual decrease in the number of nerve cells throughout the The outermost layer of the brain, the cortex is rich in neurons and is the site of most sophisticated neural processing (See also: cerebral cortex). Or, more generally, the outermost portion of certain biological structures (See below). The human cortex is 1-4mm thick, with an area (if it were... cortex follows. A few years ago, The Johns Hopkins University is an internationally prestigious private institution of higher learning located in Baltimore, Maryland. Johns Hopkins offers undergraduate and graduate programs based at the Homewood Campus in Baltimore: The Zanvyl Krieger School of Arts & Sciences and the G.W.C. Whiting School of Engineering boast a... Johns Hopkins scientists created a genetically engineered Binomial name Mus musculus Linnaeus, 1758 Mus musculus is the house mouse. This mouse is believed to be the second most populous mammalian species on Earth, after Homo sapiens; they almost always live in close proximity of humans. Laboratory mice are strains of house mice that form important model organisms... 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 An animal model usually refers to a non-human animal with a disease or altered health state that is similar to a human condition, these test subjects are often termed as animal models of disease. The use of animal models allow researchers to experiment with less restriction caused by ethical... 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, and all remain highly controversial.

Down syndrome's sociology

Advocates for people with Down Syndrome stress that they have the same Human rights are rights which some hold to be inalienable and belonging to all humans. They are necessary for freedom and the maintenance of a reasonable quality of life. If a right is inalienable, that means it cannot be bestowed, granted, limited, bartered away, or sold away (e.g., one... human rights and In psychology and common terminology, emotion is the language of a persons internal state of being, normally based in or tied to their internal (physical) and external (social) sensory feeling. Love, hate, courage, fear, joy, and sadness can all be described in both psychological and physiological terms: Emotion is... emotions as any other human being. The abuse and forcible Institutionalization is a term used to describe both the treatment of, and damage caused to, vulnerable human beings by the oppressive or corrupt application of inflexible systems of social, medical, or legal controls by publicly owned or not-for-profit organisations originally created for beneficial purposes and intents. Some modern... institutionalization of people with Down syndrome was closely linked to early (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999... twentieth-century This article is about race as an intraspecies classification. For the many types of competitive sport, see Racing. For racing conditions associated with computer programming, see Race hazard. A race is a distinct population of humans distinguished in some way from other humans. The most widely observed races are those... racial and The word eugenics (from the Greek εὐγενής, for well-born) was coined in 1883 by Sir Francis Galton, a cousin of Charles Darwin, to refer to the study and use of selective breeding (of animals or humans) to improve a species over generations, specifically... eugenic theory, culminating in the murder of many people with Down syndrome and other disabilities by the The Nazi party used a right-facing swastika as their symbol and the red and black colors were said to represent Blut und Boden (blood and soil). Black, white, and red were in fact the colors of the old North German Confederation flag (invented by Otto von Bismarck, based on... Nazi government in The Federal Republic of Germany ( German: Bundesrepublik Deutschland) is one of the worlds leading industrialised countries, located in the heart of Europe. Due to its central location, Germany has more neighbours than any other European country: these are Denmark in the north, Poland and the Czech Republic in the... Germany in the Events and trends Technology Jet engine invented Science Nuclear fission discovered by Otto Hahn, Lise Meitner and Fritz Strassmann Pluto, the ninth planet from the Sun, is discovered by Clyde Tombaugh British biologist Arthur Tansley coins term ecosystem War, peace and politics Socialists proclaim The death of Capitalism Rise to... 1930s- 1945 was a common year starting on Monday (link will take you to calendar). Events January January 5 - The Soviet Union recognizes the new pro-Soviet government of Poland. January 7 - British General Bernard Montgomery holds a press conference in which he claims credit for victory in the Battle of... 1945, and the creation of Compulsory sterilization programs sprouted up in many countries at the beginning of the 20th century, usually as part of a program of negative eugenics -- to prevent undesirable members of the population from reproducing. They generally specified that an institution or legal body could order that an individual be operated upon... compulsory sterilization programs around the world which targeted the mentally disabled.

Today, Down Syndrome is considered a ground for Abortion, in its most common usage, refers to the voluntary or induced termination of pregnancy, generally through the use of surgical procedures or drugs. As a result, birth does not take place. Medically, the term also refers to the early termination of a pregnancy by natural causes (spontaneous abortion or... abortion in an increasing number of countries. The number of children born with Down Syndrome is decreasing due to a large number of abortions after an early diagnosis of Down Syndrome during pregnancy. In a hearing before the German Parliament, doctors stated that 90% of all children Prenatal diagnosis is the diagnosis of disease or condition in a fetus or embryo before it is born. The aim is to detect birth defects such as neural tube problems, chromosomal abnormalities and other conditions to prepare the parents for the birth. Genetic counseling often accompanies prenatal diagnosis. There are... 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 p.a. were listed in the 1995 birth register.

Providing what advocates call outdated and biased information on the personality of a child with Down Syndrome, doctors often encourage mothers to have abortions. Changes in sociological theories and long standing knowledge from special pedagogics have not had a noticeable impact on medical professionals' views on raising a developmentally disabled child. Teachers trained in special education or Down Syndrome parenting groups can provide thoroughly researched information and organize encounters with disabled children, giving future mothers first hand information on life with a disabled child.

It has been widely recognized in democratic countries that the housing of people with Down syndrome in psychiatric institutions and their exclusion from society is inapt and ignores their abilities as well as their human rights. Under the influence of social role validation and inclusion, people with Down syndrome are increasingly being offered better chances for realising their potential for personal and social development. Despite this welcome change, the reduced abilities of people with Down syndrome pose a practical and ethical problem to their parents and families. While living with their parents is preferable to institutionalization for most adults with Down syndrome, they are often treated as children (and not as mentally disabled adults) for all their lives. A different and even more serious problem emerges when the parents die and leave the adult with Down syndrome behind. If there are no siblings willing or able to take the disabled person in, some institution will have to provide an apt and comfortable environment for the person with Down syndrome, as they are usually unable to run their own household, apply for a regular job, get a driver's licence and take care of insurances etc. One increasingly popular model in Europe lets four to six people with Down Syndrome share an apartment in a normal residential area, taking care of the daily household duties themselves and receiving support from a skilled caregiver in organizing their routines and in dealing with institutions or potential employers.

Many children 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. Many children with Down syndrome do have difficulties reading and understanding more than a rather basic vocabulary. Complex thinking as required in sciences but also in history, the arts and other subjects is usually beyond their abilities. Therefore, if they are to benefit from being mainstreamed without feeling inferior most of the time, special adjustments must be made to the curriculum. Some European countries such as Germany and Denmark advise a two-teacher system where 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 in order to neither slow down the non-disabled students nor neglect the disabled ones. Social activites, 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 ([2] (http://www.newscientist.com/news/news.jsp?id=ns99992073)) thanks mainly to improved diet, housing, health and social care. Many children and adults with Down's syndrome enjoy a satisfactory quality of life, and the extra chromosome may confer some health benefits, for example, reduced incidence of certain cancers caused by double immunity: lung cancer, for instance, is virtually unknown in people with Down syndrome.

Encyclopedia > Down's syndrome

Overview

Medical research

Down syndrome's sociology

Notable individuals

Down syndrome in fiction

Further Reading

External links