Down Syndrome : A Congenital Disorder Arising From A Chromosome Defect

. Down syndrome is not a disease that someone catches and is not caused by difficulties during the pregnancy, it is a genetic condition. This condition is caused by the presence of an extra chromosome in the body’s cells and causes a redundant amount of proteins to be formed. All cells of the body derive from a single cell formed by the fusion of a father’s sperm and a mother’s egg. Each cell carries a nucleus full of genetic material known as genes. These genes are inherited from both the mother and father. Each cell normally contains 46 pairs of chromosomes. 23 chromosomes come from one parent and 23 from the other, hence the 46 pairs. When it comes to children with down syndrome, one of the chromosomes does not separate properly and so the

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).

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)

Down syndrome (Trisomy of Chromosome 21) occurs when there is a defect during meiosis, typically after a mother’s egg cells have remained in suspension for a prolonged period of time (risk increases with age) or during translocation errors during early embryonic development. Individuals with Down Syndrome present physical findings of a low nasal bridge, hypotonia, lowered ears, and short stature. Patients with Down syndrome may present signs of Alzheimer’s disease around 40 years of age.

The etiology of Down syndrome is due to a genetic mutation within chromosome 21. There are three types of Down syndrome, which include Trisomy 21, Mosaic Down Syndrome, and Translocation Down Syndrome. Trisomy 21 occurs when there are three copies of chromosome 21 in each nucleus, instead of the usual two. This type of Down syndrome occurs 95% of the time. Mosaic Down Syndrome occurs 1% of the time and is characterized by some cells having three pairs of chromosome 21 and others having the normal two. This is caused by abnormal cell division after

Down Syndrome is not commonly genetically passed down as opposed to what some may think, it happens by random. About 1% of the cases are heredity and 5% come from the father. Although, the risk of having a child diagnosed with down syndrome increase dramatically past the age of 35. “A 35-year-old woman has about a one in 350 chance of conceiving a child with Down syndrome, and this chance increases gradually to 1 in 100 by age 40.” (ndss)

Down syndrome is a genetic disorder and the most common autosomal chromosome abnormality in humans. Down syndrome occurs when an individual has a full or partial extra copy of chromosome 21. This additional genetic material alters of development and causes the characteristics associated with Down syndrome. The primary purposes of this article are to: establish the origin of the term Down syndrome; determine the possible causes of Down syndrome; Likelihood of having a child with Down syndrome; and treatments for humans diagnosed with Down syndrome.

of babies born with Down syndrome elevated by about 30 percent. The risk of a child having

The possessor of this genotype has the genetic disorder called Down syndrome. Down syndrome is caused by this person having chromosome 21, which is also called Trisomy 21. There are different things you see in people with Down syndrome such as, different physical and mental traits. This genetic condition varies between each person with this genetic disorder. They all have similar features, but do not look the same.

Down syndrome is a disorder in which an individual gets a full or partial extra copy of chromosome 21. Normally, at the time of conception a baby inherits genetic information from its parents in the form of 46 chromosomes: 23 from the mother and 23 from the father, but in most cases of Down syndrome a child gets an extra chromosome 21 for a total of 47 chromosomes instead of 46. The three types of Down syndrome are trisomy 21 (nondisjunction), translocation and mosaicism. According to the National Down Syndrome Society (2012), “One in every 691 babies in the United States is born with down syndrome, making down syndrome the most common genetic condition. Approximately 400,000 Americans have Down syndrome and about 6,000 babies with Down syndrome are born in the United States each year.” Down syndrome causes intellectual disability, developmental delays, and a distinct facial appearance such as a small head, a flattened face especially the bridge of the nose, an almond-shaped eyes that slant up, a short neck, small ears, a tongue that tends to stick out of the mouth, tiny white spots on the iris of the eye, small hands and feet, a single line across the palm of the hand (palmar crease), poor muscle tone or loose joints, and shorter in height as children and adults.

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

Cells are the basis for human life. During conception, a sperm cell joins a fertile egg to begin the process of procreation. Contained in the nucleus of these cells are a threadlike structure made up of acids and proteins called chromosomes which carry genetic information. Each human cell contains 23 pairs of chromosomes in each cell for a total of 46 chromosomes (Wiseman et al., 2009). When a sperm cell with 23 chromosomes and an egg with 23 chromosomes unite, they begin to form a fetus with appropriate genetic makeup. In some cases, however, sperm cells and eggs have extra chromosomes which result in genetic disorders. Down syndrome is one of the most common genetic disorders in humans and is the result of an abnormality of chromosome 21 (Patterson, 2009).

Human cells normally contain 23 pairs of chromosomes one in each pair comes from the father and the mother. Down syndrome results when abnormal cell division involving chromosome 21 occurs. These cell division abnormalities result in extra genetic material from chromosome 21 which is responsible for the characteristics features and development problems of Down syndrome. Trisomy 21 – about 95% of the time Down Syndrome is caused by Trisomy 21, where the child has three copies of Chromosome 21 (instead of the usual two copies) in all cells. This is caused by abnormal cell division during the development of the sperm cell or the egg cell (Flood, 2013)

Typically, the nucleus of each cell stores forty-six chromosomes. Half of these chromosomes derive from each parent cell. However, in those with Down syndrome, the cells contain forty-seven chromosomes. Researchers’ knowledge of the etiology of Down syndrome has grown since it was first described in 1866 by John Langon Down (National Down Syndrome Society, 2012). According to the National Down Syndrome Association (2012), 95% of the Down syndrome cases are caused by a fault in cell division. Although it is clear that this disorder occurs because of an alteration during cell division, the cause as to why this occurs is unknown. However, the pathogenesis of this disorder is clear. The pathogenesis of this disorder begins with nondisjunction during meiosis, which is failure of the chromosomes to separate. Today, it is known that there