Genetic Disorders: Trisomy Down Syndrome

Down syndrome is a genetic disorder that numerous individuals around the world suffer from; it is an intellectual disability that is caused by having one too many chromosome 21 copies, trisomy 21. The average person has two copies of chromosome 21 in each cell, whereas, an individual with Down syndrome has an extra copy of chromosome 21. This happens when either the sperm or egg cell undergoes atypical cell division during development. In the United States, there are approximately 400,000 individuals who have been diagnosed with Down syndrome, according to the last census in 2012 (National Down Syndrome Society).

Down Syndrome is a chromosomal condition related to chromosome 21. It affects 1 in 800 to 1 in 1000 born infants. People who have Down Syndrome have learning difficulties, mental retardation, a different facial appearance, and poor muscle tone (hypotonia) in infancy.

Also known as Trisomy 21, Down Syndrome is an illness due to which an superfluous genetic structure leads to delays in the manner in which a child’s mental and physical faculties develop.

Down Syndrome is a genetic disorder that occurs when a persons 46 chromosomes abnormally divides into 47 chromosomes, creating a full or partial 3rd copy of the chromosome 21.

Down syndrome is inherited because of a chromosomal error. It occurs when someone gains an extra 21 chromosome. Usually, an individual will inherit two copies of chromosome 21, one from each parent. The extra 21 chromosomes can be inherited in three different ways, which results in three different types of Down syndrome: trisomy 21 (nondisjunction), mosaicism, and translocation. Trisomy 21 or nondisjunction is the most common form of Down syndrome; responsible for 95 percent of all the cases of Down syndrome. In this type of Down syndrome, the embryo contains three 21 chromosomes which is the result of the sperm or egg cell failing to

There are three forms of Down Syndrome. These three are Trisomy 21, Mosaicism, and Translocation. Trisomy 21 is where there is an extra copy of Chromosome 21 in every cell. Mosaicism is where only some of the child’s cells have an extra copy of Chromosome 21. Translocation is where only one of the 46 total chromosomes has an extra Chromosome 21 where part of Chromosome 21 gets attacked to another chromosome during the formation eggs and sperm, or early in the development of the fetus. Mosaicism and Translocation usually have less symptoms that Trisomy 21. Only translocation Down Syndrome can be inherited by an unaffected parent. Trisomy 21 is because of an abnormality in the reproductive cells, and mosaic Down Syndrome is just a random event that occurs early in fetal development. A baby receives 23 chromosomes from each parent, but with a Down Syndrome child, they receive extra chromosomes. When the Chromosome 21 is supposed to split into two chromosomes, the chromosome does not separate properly and they get three Chromosome 21. So as the brain and physical features develop, problems occur. Down Syndrome affects 1 in 800 newborns. Each year in the United States, 5,300 babies with Down Syndrome are born, and 250,000 people have this condition in

Down syndrome, also known as Trisomy 21, is a genetic disorder. It is caused by an abnormality in the number of chromosomes. DNA (deoxyribose nucleic acid) chromosomes are originate in the cell and are comprised of genes, which decide hereditary traits (Epstein pg.199). If a person has an extra chromosome on chromosome number 21 out of 23 they will have Down syndrome. The extra chromosome may delay the growth of a child’s physical and mental development which may lead to mental retardation. Normally, a person has 46 chromosomes, and will receive 23 pairs of chromosomes from the mother and 23 from the father totaling 46. But someone with Down syndrome will have 47. Although many theories have been developed, it is not known what actually

Down Syndrome, also known a Trisomy 21, is the most common cause of Mental deficiency that occurs from childbirth. Down syndrome is a genetic disorder that occurs when there is an extra chromosome Present. The presence of an extra chromosome causes this genetic disorder because chromosomes contain all of our genetic information and when this information is disrupted during cell division for example, when one is conceived with an added chromosome this causes many problems with the coding of the DNA. down syndrome occurs during cell division in early fetal stages. usually one inherits 23 chromosomes from each parent but in some cases people inherit an extra chromosome and receive three sets of chromosome 21, this is when the genetic disorder

Trisomy 21(Down Syndrome) is one of the most common types of chromosomal mutation. First published by John Langdon Down in 1866 and associated with chromosomes in 1959 by Jerome Lejeune, this mutation has affected thousands of infants around the world. The main cause for Down Syndrome is the formation of a 2 chromosome coming together in addition to another that does not belong. This produces extra genetic material. This occurs in the 21st chromosome of a human karyotype and this causes the newborn to have 47 chromosomes instead of the normal 46 chromosomes. So when the egg and the sperm come together there is an uneven amount of chromosomes coming from each parent.

Down syndrome is caused by a person having three copies of chromosome 21 instead of two copies. Down syndrome is also known by another name called trisomy 21. In the picture above it shows a genetic analysis of a person with down syndrome. If you notice in the picture there are 2 sets of chromosome except for the 21st chromosome set there is a pair of three. This is important to notice because chromosome sets are supposed to be in sets of two. It's a fact that the three chromosomes in set 21 are what causes down syndrome. Every cell in a person with down syndrome will contain 47 chromosomes instead of 46 chromosomes. “There are many theories that may be the cause of having an extra cell to react inside the chromosome that causes down syndrome

There are three different types of Down syndrome: Trisomy 21, Mosaic, and Translocation. The most common type of Down syndrome is Trisomy 21, “affected[ing] 95% of people with Down syndrome, and occurs when each cell in the body has three separate copies of chromosome 21” (“Facts About Down Syndrome”). Of the 95% of people with Trisomy 21 down syndrome, they all share one thing. They all have three separate copies of the 21st chromosome, instead of the normal two copies. The second most common type of Down syndrome is Translocation Down syndrome, “[It] accounts for about three percent of people with Down syndrome, and occurs when there is an extra part or a whole extra copy of the 21st chromosome”) (“Facts About Down Syndrome”). Translocation down syndrome is a very unique type of Down syndrome, and differs from Trisomy 21 greatly. Translocation down syndrome occurs when the body started to make a third copy of the 21st chromosome ( which would have led to Trisomy 21),

Down syndrome, also known as trisomy 21, is a genetic disorder caused by a third duplicate of chromosome 21. Down syndrome was first recognized as a distinct condition in 1866 by John Langdon Down, after whom the disease is named. Until 1970, the disorder was known as Mongolism and only recently become accepted as “down” syndrome. In 1959, French geneticist Professor Jerome Jejune discovered an extra chromosome to be the cause for the physical and intellectual abnormalities seen in individuals with DS. (Kazemi, Shojaei, & Sadighi, 2016). Down syndrome affects approximately one in every 1200 babies that are born, making it the most common genetic disorder. (Jobling, Virji- Babuls, & Nichols, 2006).

Mosaicism is diagnosed as a combination of two types of cells, some have the usual 46 chromosomes and some have 47. The cells with 47 chromosomes have an extra chromosome 21. Mosaicism accounts for only about 1% of the cases of Down syndrome and is the least common

Down syndrome or another name known as trisomy 21 is a genetic disorder that is caused when there is a chromosomal mistake that occurs during meiosis that leaves an extra chromosome. A lot of the time a break occurs in the fourteenth and the twenty first chromosome, this is called Robertsonian Translocation. Breaks can occur in other areas however it seems that Robertsonian Translocation is the most common.

     Mosaic Trisomy 21 happens when an egg or sperm come in with an extra copy of chromosome 21, then,