Down Syndrome Trisomy 21, Translocation And Mosaicism

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).

Trisomy 21, most commonly known as Down Syndrom is a congenital chromosomal condition in which an individual possesses a complete or partial duplicate of the twenty-first chromosome;whereas, the typical person has a total of 46 chromosomes, a person with Dien Syndrome has 47. This may not seem like a big deal, but this disorder results in varying degrees of mental

Down syndrome is caused by having an extra chromosome on the twenty-first chromosomal pair. People with down syndrome have forty-seven pairs of chromosomes. There are three types of down syndrome and they are Trisomy 21, Translocation, and Mosaicism. Trisomy 21 is the most common type of down syndrome. It occurs when there are three rather than two, number 21 chromosomes present in every cell of the body. Trisomy 21 accounts for ninety-five percent of the down syndrome population. Translocation unlike Trisomy 21 only accounts for four percent of the down syndrome population. In this case, part of the twenty-first chromosome breaks off during cell divas and attaches itself to another chromosome, usually chromosome 14. Mosaicism is the rarest

One of the most common genetic birth defects is Down syndrome which is a congenital disorder caused from a chromosome defect. It causes impairments and physical abnormalities. This is a condition where a child is born with an extra copy of their 21st chromosome. According to the National Down Syndrome Society (NDSS), 1 in 700 babies are born with DS. There is not an exact cause of how DS happens but there is an explanation as to what happens. When there is any case of reproduction, genes from both parents are passed to the children. Within these genes there are chromosomes and the child is supposed to receive 23 pairs of chromosomes or 46 total. Children with DS end up with 3 copies or an extra partial copy of chromosome 21 instead of 2

Down syndrome is caused by an extra chromosome of 21 in the children’s cell. Normally people have 46 chromosomes, however down syndrome contains 47 chromosomes. (Nhs.uk, 2016i)

Trisomy 21 most commonly known as Down syndrome is a genetic disorder that causes abnormal cell division resulting an extra genetic material forming a twenty-first chromosome. No one knows for sure why Down Syndrome happens and there is no way to prevent the chromosomal error that causes it. Scientists knows that women age thirty-five and older have a significantly higher risk

Down syndrome is a genetic defect attributed to an abnormality of the human chromosome 21. The National Down Syndrome Society (NDSS), a national advocate organization for the value, acceptance and inclusion of people with Down syndrome, notes that modern research has successfully identified three types of Down syndrome. The NDSS reports that Nondisjunction Trisomy 21, in which there are three copies of chromosome 21 instead of two, is the most common type of Down syndrome. Prior to or at the point of conception, a pair of 21st chromosomes in either the

Down Syndrome (DS) or trisomy 21 is a condition where “the third copy of chromosome 21 disturbs the expression of all DNA in the genome” (Study revises cause of down syndrome, 2014, p.1). This genetic condition is responsible for

Down syndrome (trisomy 21) is a chromosomal abnormality - change in the number of chromosomes, which lead to physical or mental abnormalities - caused by an error in cell division that is a result of having an extra 21st chromosome. 95% of the time the trisomy is mainly due to an abnormality of the egg of a mother, during fertilisation the 23 chromosomes from

Down syndrome is characterized as a chronic genetic chromosomal disorder which alters one’s cognitive growth, intellectual development, and physical characteristics. This extremely widespread condition is most prominently existent in human beings whose genetic makeup is composed of an additional copy of chromosome 21. Additionally, these human beings are known for acquiring 47 chromosomes rather than the conventional 46 chromosomes. This chromosomal abnormality is extremely common, yet highly spontaneous. To illustrate, the prevalence of Down Syndrome is exhibited as around

It's hard to believe a random error in cell division known as nondisjunction can be the reason for so many birth defects. This one mistake is the cause of 1 in 691 babies being born with what is known as Down Syndrome. In every cell in the human body, there is a nucleus. Typically there are twenty three chromosomes in each nucleus. Down Syndrome occurs when there is extra full or partial copy of chromosome 21. Down Syndrome is a chromosomal condition that causes low muscle tone, small stature, and a single deep crease across the center of the palm. Although, each person with Down Syndrome is a unique individual and may have these characteristics to different degrees.

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).

Nondisjunction is the error in cell division that usually causes Down syndrome. Nondisjunction causes an embryo to have three copies of chromosome 21 instead of the usual two. Sometime prior to, or at conception, a pair of number 21 chromosomes, either in the sperm or the egg, fail to separate. Trisomy 21 happens in the egg 95 percent of cases and in the sperm only five percent. The extra chromosome replicates in every cell of the body as the embryo develops. Trisomy 21 accounts for about 95% of cases.

Chromosomes are the units of genetic information that exist within every cell of the body. Twenty-three distinctive pairs, or 46 total chromosomes, are located within the nucleus (central structure) of each cell. When a baby is conceived by the combining of one sperm cell with one egg cell, the baby receives 23 chromosomes from each parent, for a total of 46 chromosomes. Sometimes, an accident in the production of a sperm or egg cell causes that cell to contain 24 chromosomes. This event is referred to as nondisjunction. When this defective cell is involved in the conception of a baby, that baby will have a total of 47 chromosomes. The extra chromosome in Down syndrome is labeled number 21. For this reason, the existence of three such chromosomes

Cause/ Type of mutation: The most common form of Down syndrome is identified as trisomy 21. It’s a condition in which individuals have 47 chromosomes in each cell instead of 46. The cause of trisomy 21 is due to an error in cell division which is identified as nondisjunction in which leaves a sperm or egg cell with an extra copy of chromosomes 21 before or at conception.