Down syndrome (DS) is an unpreventable, chromosomal disorder characterized by excessive genetic material which hinders the ongoing progression of a child’s growth that, involves physical and intellectual development. In the majority of the cases, DS is caused by Trisomy 21 –a chromosomal defect, where there are three copies of chromosome 21 in each of the cells, instead of the norm of two. Generally, Down syndrome is not hereditary since it is caused by a blunder in the process of cell division during the formation of the reproductive cells from one of the parents. There is evidence that mothers over the maternal age of thirty-five are more susceptible to having a child with DS. The prevalence of DS in Canada, is approximately 1 in every 800 live births. It is often diagnosed in early infancy by the examination of specific characteristics linked to the baby’s appearance – such as hypotonia (low muscle tone), palmer’s crease, slightly flattened facial profile, an upward slant to the eyes, small mouth, and protruding tongue. (HudsonAlpha, 2012) However, prenatal screening and blood tests can also determine if the baby is at any subsequent risk of having DS for early prognosis and intervention. Cognitive deficits such as intellectual disabilities are redundant in DS. The degree of intellectual disabilities range from normal to severe and, approximately 80% of the individuals with DS suffer from a type of intellectual disability. (Roberts et al., 2007) Children with Down syndrome are more prone to frequent ear infections which leads to decreased hearing abilities and delayed language acquisition displayed in normal children. According to Chapman et al., (2000), the loss of hearing appears to be a chronic issue through... ... middle of paper ... ...s that can help them to have mundane lives. The key to improvement for language difficulties in individuals with DS, is early intervention which may yield many opportunities for an optimistic future. Advancement in health care and science today, have impacted the world and contributed to the lives of individuals with DS, positively. Their life expectancy as we know today, have increased dramatically in contrast to the past. It is evident that the language learning process for individuals with DS is long-term and increases with the aid of special education, occupational, speech, and language therapy, and physiotherapy. We need to encourage more research on the different areas in language development such as; phonology, syntax, semantics, and pragmatics to new heights, and continue to discover more efficient ways that can be beneficial to individuals with DS.
Down syndrome is a disorder that comes with some defects, such as in the face, heart, sight, and hearing, and other health related problems. It also is the most common genetic defect, affecting many babies. Down syndrome is caused when the chromosomes are being divided during meiosis the cell keeps both copies of chromosome #21, which means the person with Down syndrome has an extra copy in every cell in their body. This is a sad genetic disorder that can change a person's life. Even though it is a devastating gene mutation, the people with Down syndrome are some of the most loving of all people.
is a hereditary predisposition to this disorder. Also, the way a child is raised can greatly increase
Down Syndrome results when one of the three types of abnormal cell divisions involving chromosome 21 occur. Roger W. Harms, a medical doctor, states, “Human cells normally contain twenty-three pairs of chromosomes. One pair comes from your father and one pair comes from your mother.” In each pair, one chromosome comes from the father, and one comes from the mother. One of the three genetic variations that can cause Down Syndrome is Trisomy 21. This version of Down Syndrome occurs more than 90% of the time. It re...
Birth defects. (2013, November 6). Retrieved January 19, 2014, from Centers of Disease Control and Prevention website: http://www.cdc.gov/ncbddd/birthdefects/DownSyndrome.html
Since the gene for HD is dominant, there is a 50% chance of a sufferer's
of as a likely cause since children who have a parent with the disorder have a
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.
Down syndrome, also known as “trisomy 21” is a genetic condition in which a child is born with an extra chromosone which causes certain features and delays in development. In sexual reproduction (meiosis) the new cell will have half of the mothers chromosones 23 and half of the fathers chromosones 23 to make a total of 46 (23 pairs) in the new cell (zygote). In a child with Down Syndrome, they will have an extra chromosone 21 making a total of 47 chromosones. There is no specific reason why this extra chromosone is present, but the older the mother is when giving birth, the more likely that her baby will have Down syndrome. Down Sydrome is named after John Langdon Down, the first person to describe the condition in 1866.
Internationally it is estimated that the number of individuals born with FASD ranges from 1-3 per 1000 live births in the general population to as many as 9.1 per 1000 live births among high-risk populations, making FASD a substantial global concern.
Mosaicism is when non-disjunction occurs in one cell division after fertilization causing a mixture of two types of cells. Some of these cells contain 46 chromosomes others contain 47 chromosomes. This type of Down syndrome is very rare and is less affected. Mosaicism is responsible for 1-2 percent of Downs.
The most common type of Down syndrome is Trisomy 21. It is where the body has 47 Chromosomes instead of 46 (Crosta). Trisomy 21 is caused by a problem in the cell division called non-disjunction. It leaves a sperm or an egg cell with an extra copy of chromosome 21.... ... middle of paper ...
Mosaic Trisomy 21 happens when an egg or sperm come in with an extra copy of chromosome 21, then, once an embryo is formed and starts to develop, the chromosome is replicated in some of the cells. In Mosaic some cells have a normal number of chromosomes and some have an extra chromosome 21. Mosaic Trisomy 21 occurs in 2-3% of patients with Down syndrome. Mosaic Trisomy produces a wide range of possibility of a person having physical problems.
Down syndrome can be caused for three different reasons. The most prevalent reason is called trisomy 21. This means that rather than having 46 chromosomes you have 47. This is the cause for approximately ninety- five percent of the people affected by Down syndrome. The extra chromosome is usually found on the twenty-first pair. The next cause only affects 1 percent of the Downs population. It is known as mosaicism. This is caused from an error during cell division right after conception has occurred. It has been seen that with mosaicism some of the cells have 47 chromosomes while other cells only have 46 chromosomes. The last reason can be traced back to the parent's. It is known as translocation. The twenty-first chromosome is translocated on to another chromosome. The parents could be carrying the chromosome that translocates. This form of Down syndrome affects only 3-4 percent of the people living with Downs.
Most individuals are either related to or know someone who is effected by some type of disability. Many of these disabilities are caused by genetic disorders. Genetic disorders may alter physical appearance and cause mild to severe mental retardation. Fragile X syndrome, Down syndrome, Turners syndrome and many other syndromes result from a mutation of a chromosome, an extra chromosome, or too few chromosomes.