What is Down syndrome?

Down syndrome is genetic disorder that causes lifelong mental retardation, developmental delays and other problems. Down syndrome varies in severity, so development problems range from moderate to serious. Down syndrome is the most common genetic cause of severe learning disabilities in children, occurring in one in every 700 to 800 infants. Increased understanding of
Down syndrome and early interventions make a big difference in the lives of both children and adults with Down syndrome. Down syndrome is also known as Trisomy 21 syndrome. Trisomy 21 is due to an extra copy of chromosomes number 21. Instead of having the normal two copies chromosomes number 21, the person with Down syndrome has three copies of chromosomes 21. Meaning normally a fertilized egg has 23 pairs of chromosomes. In most people with Down syndrome, there is an extra copy of chromosome 21. (Rogers, 2007, pg.6) The formal story began in 1866, when a physician named John Langdon Down published an essay in England in which he described a set of children with common features who were distinct from other children with mental retardation. Down was superintendent of an asylum for children with mental retardation in Surrey, England when he made the first distinction between children who were cretins (later to be found to have hypothyroidism) and what he referred to as "Mongoloids." Down based this unfortunate name on his notion that these children looked like people from Mongolia, who were thought then to have an arrested development. This ethnic insult came under fire in the early 1960s from Asian genetic researchers, and the term was dropped from scientific use. Instead, the condition became called "Down's syndrome." In the 1970s, an American revision of scientific terms changed it simply to "Down syndrome," while it still is called "Down's" in the UK and some places in Europe. In the first part of the twentieth century, there was much speculation of the cause of Down syndrome. The first people to speculate that it might be due to chromosomal abnormalities were Waardenburg and Bleyer in the 1930s. But it wasn't until 1959 that Jerome Lejeune and Patricia Jacobs, working independently, first determined the cause to be trisomy (triplication) of the 21st chromosome. Cases of Down syndrome due to translocation and mosaicism were described over the next three years. (Leshin, 2009, pg. 2)

Signs and Symptoms of Down syndrome

Even though people with Down syndrome may have some physical and mental features in common, symptoms of Down syndrome can range from mild to severe. Usually, mental development and physical development are slower in people with Down syndrome than those without the condition. Most people with Down syndrome have IQs that fall mild to moderate range of IDDs. They may have delayed language development and s low motor development. Some physical features of Down syndrome include flat face with upward slant to the eye, short neck, abnormally shaped ears, deep crease in the palm of the hand, white spots on the iris of the eye, poor muscle tone, ligaments and small hands and feet. (Fisher,2008, pg. 860) A child may have other medical conditions related to Down syndrome, such as Intellectual disability. Most children with Down syndrome have mild to moderate cognitive disability. They may also have defects; about half of the children who have Down syndrome are born with a heart defect. Most defects are diagnosed at birth or shortly after birth. Children with Down syndrome are also prone to developing other health problems. For example, respiratory infections, hearing problems, and dental problems are common.
Etiology
Down Syndrome is the most common cause of mental retardation and malformation in a newborn. Individuals with Down Syndrome have a tendency to be overweight. Future conditions for individual’s with Down Syndrome include; an inability to ever reach normal growth development, possibility of poor hearing, heart conditions that will affect activity and fitness levels through life, and a faster aging process with a tendency to develop diseases of aging like Alzheimer’s at an early age. Also, individuals with Down Syndrome are affected by certain eye disorders including Strabismus (crossed eyes), which affects tracking skills and binocular vision throughout life.

Risk Factors
About 50 percent of babies with Down syndrome have a congenital heart defect. Some defects are minor and may be treated with medications, while others may require surgery. All babies with Down syndrome should be examined by a pediatric cardiologist, a physician who specializes in heart diseases of children, and have an echocardiogram (a procedure that evaluates the structure and function of the heart by using sound waves recorded on an electronic sensor that produce a moving picture of the heart and heart valves) in the first two months of life, so that any heart defects can be treated. About 10 percent of babies with Down syndrome are born with intestinal malformations that require surgery. Children with Down syndrome are also at increased risk for visual and hearing impairment. Common visual problems include crossed eyes, near- or farsightedness, and cataracts. Most visual problems can be improved with glasses, surgery, or other treatments. A pediatric ophthalmologist (a physician who specializes in comprehensive eye care and provides examinations, diagnosis, and treatment for a variety of eye disorders) should be consulted within the first year of life. Children with Down syndrome may have hearing loss due to fluid in the middle ear, a nerve defect, or both. All children with Down syndrome should have regular vision and hearing examinations so any problems can be treated before they hinder development of language and other skills. Children with Down syndrome are at increased risk of thyroid problems and leukemia. They also tend to have many colds, as well as bronchitis and pneumonia. Children with Down syndrome should receive regular medical care including childhood immunizations. The National Down Syndrome Congress publishes a "Preventative Medicine Checklist" which outlines which checkups and medical tests are recommended at various ages. (Packyard, 2009, pg.23)