Essay Example on What is Down Syndrome

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What is Down syndrome Down syndrome occurs when an individual has a full or partial extra copy of chromosome 21 Typically the nucleus of each cell contains 23 pairs of chromosomes This additional chromosome alters the course of development Some of the common physical traits of Down syndrome are Low muscle tone small stature an upward slant to the eyes and a single deep crease across the center of the palm everyone with Down syndrome doesn't have the same characteristics According to the Centers for disease control and prevention around 1 in every 700 babies born in the United States have Down syndrome There are about 6 000 babies with Down syndrome born in the US each year It wasn t until the late nineteenth century that John Langdon Down published an accurate description of a person with Down Syndrome It was his work that earned the Down as the Father of the syndrome In 1959 French physician Jérôme Lejeune identified Down Syndrome as a chromosomal condition Lejeune observed that individuals with Down syndrome had 47 chromosomes present in each cell rather than the usual 46 in each cell Later on it was determined that an extra copy of chromosome 21 results in the characteristics of Down syndrome In 2000 An international team of scientists successfully identified that there were around 329 genes on chromosome 21 Discovering this information lead to huge advances in Down syndrome research Are there different types of Down syndrome Yes there are 



The most common type would be Trisomy 21 Nondisjunction Down syndrome is usually caused by nondisjunction an error in cell division Nondisjunction results in an embryo with three copies instead of two of the chromosome 21 This type of Down syndrome accounts for 95 of cases Another type is Mosaicism Mosaicism is diagnosed when there is a mixture of two types of cells some containing 46 chromosomes and some that have 47 Cells with 47 are those that contain an extra copy of chromosome 21 This is the least common form of Down Syndrome Individuals with Mosaicism may have fewer characteristics of Down syndrome than people with other forms of Down syndrome Translocation accounts for about 4 of the cases of Down syndrome The total number of chromosomes remains 46 in the cells but an additional copy of chromosome 21 usually attaches to chromosome 14 The Extra copy of chromosome 21 is what causes the characteristic of Down syndrome No matter what type of Down syndrome an individual has everyone with it has an extra copy of chromosome 21 in all or some of their cells This additional Genetic material alters the development and causes the characteristics of Down syndrome The cause of the extra chromosome 21 is still unknown The maternal age is the only factor that has been linked to having a baby with Down syndrome this is a result from Nondisjunction or Mosaicism 80 of children with Down syndrome are born to women under 35 years old because of the higher birth rates in younger women The additional copy of the 21 chromosome that causes Down syndrome can come from either the mother or the father somewhere around 5 if the cases have been traced back to the father Anyone could be born with Down syndrome it occurs in all races and economic levels Although older women have more of a chance of having a child with the syndrome 



A 35 year old women have about a 1 in 350 chance of having a child with down syndrome By age 40 women have a 1 in 100 chance of having a child with Down syndrome and at 45 women have a 1 in 30 chance The woman s age isn t linked to Translocation Many couples are posting parenting until later in life so the conception rates of down syndrome is expected to increased All three types of Down syndrome are genetic conditions but only 1 of all cases have a hereditary component In Trisomy 21 nondisjunction and mosaicism heredity is not a factor However Down syndrome resulting from translocation there is a hereditary component The ago of the mother does not seem to be a cause of translocation Most cases are sporadic events but in about one third cases one of the parents is a carrier of a translocated chromosome once a woman gives birth to a child with 



Down syndrome it is very likely that to have another because her chances goes up to 1 in 100 until age 40 The risk of recurrence of translocation is 3 if the father is the carrier and around 10 15 if the mother is the carrier How can you diagnose Down Syndrome There are two categories of test for Down Syndrome Screening tests and Diagnostic test can be performed before the baby is born You can also get prenatal screens to estimate the chances of your baby having Down Syndrome although these test do not tell you for sure if the fetus has Down syndrome Most screening test involve a blood test and a ultrasound The blood test measures the quantities of various substances in the mother's blood At birth Down syndrome is usually identified by the presence of certain physical traits including Low muscle tone a single deep crease across the hand and a slightly flattend facial profile and slightly upward slant to the eyes


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