Sometimes when meiosis ( the division of reproductive cells ) occurs, chromosomes may be lost, left behind, or too many may be passed on, resulting in the birth of a child with a genetic or congenital defect or disease. One of the most common of these genetic disorders is Down syndrome. This disorder takes its name from Dr. Langdon Down, who was the first to describe it formally, in 1866.
Down syndrome is a condition marked by abnormal physical and mental development that is caused by a genetic defect. This genetic defect is caused by an extra chromosome. People born with Down syndrome have 47 chromosomes compared to the normal amount of 46, 23 chromosomes inherited from each parent. This extra chromosome originates more often in the mother's egg than the father's sperm. Chromosomes are individual, large DNA molecules in a cell nucleus. They contain the genes along with structures that hold the DNA and aid it in expressing heredity by orchestrating cellular operations.
Down syndrome is one of the most common chromosomal abnormalities, occurring in about 1 out of 800 births. However, the frequency of the disorder varies greatly according to the age of the mother. For women in their twenties the rate is 1 in 2,000 but it rises steeply to 1 in 100 by the time a woman reaches 40.
Down syndrome is usually recognized soon after birth because of characteristic facial features such as a flattened nose, upward slanting of the eyes, a large tongue that often protrudes from a smal...
Down’s syndrome is a chromosomal condition that is caused by an extra 21st chromosome as there is an error in the body’s cell division. Every human has a nucleus in every cell in the body which contains genes that are grouped along with chromosomes. The normal number of
“About 13 of every 10,000 babies born in the United States each year is born with Down syndrome. It affects an equal number of male and female babies” (Johnson P. A. 2014). Down syndrome is a genetic disorder that found across the world, however it is more prevalent in the United States. The cause of the disorder roots to the paring of the human chromosomes. A normal human receives 23 pairs of chromosomes, each pair coming from mother and father. In Down syndrome most people affected have an abnormal cell division of the chromosome. Both parents are carriers of the There are three types of variations that includes trisomy 21, mosaic, and translocation.
Most cases of Down syndrome are not inherited. When the condition is caused by trisomy 21, the chromosomal abnormality occurs as a random event during the formation of reproductive cells in a parent. The abnormality usually occurs in egg cells, but it occasionally occurs in sperm cells. An error in cell division called nondisjunction results in a reproductive cell with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of chromosome 21. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 21 in each of the body's cells.
In 1866 British doctor John Langdon Down defined and described the characteristic symptoms of Down Syndrome but was unsure of the cause. It wasn't until 1959 that Dr. Lejeunne and his team in Paris showed that people with Down Syndrome have an additional chromosome. We normally have 23 pairs of chromosomes, each made up of genes. The cells of people with Down Syndrome include three chromosome #21 instead of two. The extra 21st chromosome causes an extra dose of proteins. These proteins cause the typical features of Down Syndrome. While the fetus with Down Syndrome is developing, its body cells do not reproduce as fast as usual. That is the main reason why these babies are smaller than average after birth and their brain not as big as those of other newborn children.
Down's syndrome is not a disease and therefore people with Down syndrome do not suffer nor are they victims of their condition.Down Syndrome is a natural disorder coming from a chromosome defect. It is a genetic condition in which a person has 47 chromosomes instead of the usual 46. Which causes mental impairment and physical deformity.For example short stature , broad facial profile and weak muscle tone.It occurs in approximately one in every 800 live births.It is the most frequently occurring chromosomal disorder. Down syndrome is not related to race, nationality, religion or socioeconomic status.(medline plus)
It is a well known fact that all living things, humans included, are made up of cells. The nucleus of a typical cell in the human body is made up of 23 pairs of chromosomes. Half of the pairs come from each parent. In some individuals there is a full or partial extra copy of chromosome 21 present; these individuals have Down Syndrome (National Down Syndrome Society). Down Syndrome is a genetic disorder that most people know very little about. Since Down Syndrome is something that very few people know much about, this paper will include a lot of information about the disorder that is not well known to the general public. In this paper I will discuss what exactly Down Syndrome is and provide background information and history, describe how and when the disorder is diagnosed, provide insight of what life is like for a person with Down Syndrome and I will do my best to clear up many misconceptions that people often have about individuals with Down Syndrome.
All three types of Down syndrome have an extra chromosome or part of chromosome 21 in one or all the cells. The extra chromosome changes the way an embryo develops and changes the physical and mental characteristics of the child. It is unknown what exactly causes nondisjunction. Although it is unknown, research has shown that the chances of having a child with Down syndrome go up as the woman’s age goes up. Even though the chances goes up the older the woman is, 80% of Down syndrome cases occur in woman under the age of 35. Although age can cause nondisjunction, there is nothing that proves that age is linked to translocation. This is due to more women having children at a younger age. Nothing as of today has been proven that any activities of the parents during or before pregnancy has affected the chance of the child developing Down syndrome. Also, there is no proof that the environment of the child causes Down syndrome. Most cases of Down syndrome have not been inherited from the parents, but 5% of the cases are due to the father’s
Down syndrome is caused by a problem with a baby’s chromosome. Chromosomes are cell structures made up genetic DNA (“Chromosomes”). Most people with Down syndrome have 47 chromosomes. This changes the way the brain
Down syndrome, a genetic disorder, is the most common cause for intellectual disabilities, occurring at an average of one out of every 700 births (CDS, 2006). This disorder is caused by the extra chromosome 21 (also known as Trisomy 21). According to Hassold and Sherman (2002), the probability of giving birth to a child with DS is not linked to any race, ethnicity, socioeconomic status or geographic location. Maternal age seems to be the only etiological factor that may cause DS.
When it comes to participating in service, I did food and friends twice with Ms. Fitzsimmons for the couple months I have been with Gonzaga. Yet before coming here, I went on a service trip to Nicaragua during my time in Costa Rica. While it was only a week, it felt like a month of spending time in Tipitapa which is the dumpsite for the
Trisomy 21 or more commonly known as down syndrome is a condition in which an individual has a full or partial extra copy of chromosome 21 (What is Down Syndrome?, 2012). It was first described as a disorder in 1866 by doctor John Langdon Down and it is the most common cause of cognitive impairment (Heyn, 2014). Today there are three known types of down syndrome trisomy 21 or called nondisjunction, translocation, and mosaicism. Regardless of the type of down syndrome a child may have, they all have an extra portion of chromosome 21 present and the cause is still unknown today (What is Down Syndrome?, 2012). With the cause unknown many people have misconceptions or don’t understand what down syndrome is. That is why I chose to research down
Down syndrome can be caused by a random error in cell division which results in a presence of an extra copy of chromosome 21. This type of error is called nondisjunction. Usually when one cell divides in two, pairs of chromosomes are split so that one of the pair goes to one cell, and the other from the pair goes to the other cell. In nondisjunction something happens that makes both chromosomes from one pair go into one cell and no chromosome from that pair goes into the other cell. A lot of the time, the error occurs at random during the formation of an egg or sperm. After a lot of research is has been discovered that in more than 90% of cases, the extra copy of chromosome 21 comes from the mother in the
The cause of this disorder is because of an extra chromosome in the body. About 90% of Down Syndrome cases are caused by this extra chromosome, chromosome 21 (this is why it is also called Trisomy 21). An extra chromosome originates in either the sperm or the egg. When the egg and the sperm unite to form the fertilized egg, two instead of three chromosomes in chromosome 21 are present. As the cells divide the extra chromosome is repeated in every cell.
Down syndrome is a common birth defect that is genetic. It is a chromosomal disorder caused by an error in cell division that results in an extra 21st chromosome. Most children born with Down syndrome have some level of mental retardation.
Down Syndrome or Trisomy 21 is an extra copy of chromosomes 21; healthy babies have two copies, while down syndrome babies have three copies. Blood tests that pregnant women get have sparked a debate about aborting unborn babies with down syndrome because the parents “can’t handle it” or “dont know how to care for a baby with a disability.”