All human beings are made up cells. In every cell, there is specific DNA that contains genetic material, which makes up a person. Genes are what is responsible for our appearance, and traits. Naturally, a cell is made up of 23 chromosomes. Whenever a person has an extra copy of chromosome 21; this individual will have Down syndrome. “It's this extra genetic material that causes the physical features and developmental delays associated with DS.” (“Down Syndrome.”). It can be inherited from one, or both of the parents. This genetic mutation affects individuals in the same way, however; it can be to different extremes. Some are mildly affected by this, while life for other people could be extremely difficult and challenging.
Down syndrome was named after John Langdon Down, the British doctor who discovered the syndrome in 1866. The syndrome was not linked to chromosome twenty- one until 1959 by Jerome Lejeune. Down syndrome, the most common genetic condition, occurs in one out of six-hundred and ninety-one kids in the United States. This syndrome is caused by an extra number twenty-one chromosome, also known as trisomy twenty-one. In most cases it is caused by nondisjunction; which is sister chromatids of the twenty first chromosome that do not separate properly causing the child to receive an entire extra copy of that chromosome. In some unique cases this syndrome can also be caused by translocation and mosaicism. Children born with Down syndrome have some very unique physical characteristics; such as, low muscle tone, slanted eyes, big mouths, and a simian crease across the palm. These characteristics and many others are common but of course not found in every case of the syndrome. One characteristic that is found in every case is some amount of cognitive delay. Most people with Down syndrome suffer mild to moderate delay, although some unique cases of the syndrome deal with very severe cognitive delay.
People with Down syndrome are first and foremost human beings who have recognizable physical characteristics and limited intellectual endowment which are due to the presence of an extra chromosome 21.
Down syndrome was first classified by Dr. John Langdon Haydon Down, who referred to persons with down syndrome as mongoloids because of their facial features being similar to those who are from Mongolia, particularly the slanted eyes (Moran). As a result this disorder was known as mongolism, but this is now considered offensive and has been recognized as Down syndrome since the early 1970s (Moran). Though Dr. Down didn't have down syndrome, he became an advocate for the proper treatment for people who were mentally handicapped. Dr. Down was the pioneer of discovering the similar traits of those who had down syndrome. However, it was the geneticist Jerome Lejeune who discovered the gene abnormality which in turn manifests the physical and mental traits Dr. Down was studying (Moran). Dr. Down showed us what Down syndrome looks like, but Jerome Lejeune showed us where it came from.
Trisomy 21 is caused, as the name suggests, by the triplication of the 21st chromosome. Genes which, simplified, contain the blueprints for our cellular structure, are grouped along rod-like structures called chromosomes. Normally, the nucleus of each cell contains 23 pairs of chromosomes, half of which are inherited from each parent. In Down syndrome (DS), however, the cells usually contain not 46, but 47 chromosomes. This excess genetic material, in the form of additional genes along the 21st chromosome, results in DS. The estimated incidence of Down syndrome is between 1 in 1,000 to 1 in 1,100 live births. Each year approximately 3,000 to 5,000 children are born with this chromosome disorder. It is believed there are about 250,000 families in the United States who are affected by DS. (Berg, 614) Discussed in this paper will be a more detailed description of the pathophysiology of Down syndrome, as well as the discovery, possible causes, physical features, associated conditions, possible treatment, electroneurodiagnostic corollaries, and psychosocial issues.
Down syndrome is a genetic alteration that occurs by the presence of an extra chromosome. The cells of the human body have 46 chromosomes in 23 pairs distributed. One of these pairs determines the sex of the individual. People with Down syndrome have three chromosomes in the pair 21 instead of the two that usually exist; therefore, this syndrome is also known as trisomy 21. Down syndrome is not a disease. This syndrome is a more common genetic alteration of mental retardation or development. Down syndrome is an abnorma...
A type of down syndrome occurs due to nondisjunction. Human beings have 23 pairs of chromos...
Down Syndrome is caused by an excess of chromosome 21 in some or all cells. “This additional genetic material alters the course of development and causes the characteristics associated with Down syndrome”(Laney 7). Chromosomes are the type of structures which the genes are contained in. Normally, every person has 23 pairs of chromosomes. A chromosome is inherited by the parents, one from the father and one from the mother. After fertilization occurs an egg commonly contains 46 chromosomes. In some cases, though, their are mishaps before fertilization. “ A developing egg or sperm cell may divide incorrectly, sometimes causing an egg or sperm cell to have an extra chromosome number 21. When this cell joins with a normal egg or sperm cell, the resulting embryo has 47 chromosomes instead of 46”(ndss). When this manifests, a child is concieved with disformities, and intellectual affliction. The...
In 1886, physician John Langdon Down was the first scientist to identify Down syndrome. Down was the administrator of a mental institute for children in Surrey, England. From his observations and work at the institute, he was able to identify a set of children who exhibited characteristics such as short nose, broad flat face, short and broad hands, which are features commonly identified with Down syndrome. He later wrote an essay entitled “Observations of the Ethnic Classification of Idiots” in which he asserts the notion that it was possible to classify different types of health conditions through race. His essay included his now famous classification of what is today known as Down syndrome, which he categorized as the Mongol...
The presence of an extra chromosome is prevalent in plants but rare in animals. Diploid human cells contain 46 chromosomes, 44 autosomes and two sex chromosomes namely XX in females and XY in males. At mitotic metaphase, each of the chromosomes can be recognized by its size, shape and banding pattern. However, there could be non-disjunction of chromosomes during the process of meiosis, and as a result, one of the cells may receive an extra copy of the chromosome resulting in a condition called trisomy. One of the most common chromosome abnormality in humans is Down Syndrome, a condition associated with an extra chromosome 21. This condition was first described by British physician, Langdon Down (Web. Down Syndrome, n.d.).