This disease can develop either before or after a child is born. Less than 1,000 pregnancies for mothers less than 30 years of age result in a baby with Down syndrome. For mothers who are 44 years of age, about 1 in 35 pregnancies results in a baby with Down syndrome (Crosta). The only way to have a child with Down syndrome is determined by the mother’s age. 75-80% of babies that have Down syndrome are born to younger mothers.
Instead of the normal number of 46 chromosomes in eachcell, the individual with Down syndrome has 47 chromosomes. This condition is called trisomy 21. The second type is called translocation since the extra 21 chromosome is attached or translocated on to another chromosome, usually on chromosome 14, 21 or 22. If translocation is found in a child with Down syndrome, it is important to examine the parents’ chromosomes, since in at least one-third of the cases, a parent may be a carrier of the translocation. This form of chromosome error is found in 3 - 4 percent of the individuals with Down syndrome.
Down syndrome is a genetic disease where there is an extra chromosome on the 21st chromosome. Now there are three types of Down syndrome Trisomy 21, Mosaic Down syndrome, and Translocation Down syndrome. First we’ll talk about Trisomy 21. According to Mayo Clinic Staff (2011) “More than 90 percent of the time, Down syndrome is caused by trisomy 21. A child with trisomy 21 has three copies of chromosome 21 — instead of the usual two copies — in all of his or her cells.”(Para.3) so from this we can conclude that this is the most common type of Down syndrome.
Instead of 46 chromosomes in each cell it was determined that an extra 21st chromosome affected Down syndrome, this occurs 95% of the time. There are three copies of this chromosome. It is causes by a cell error called non-disjunction. Two other types are mosaicism and translocation. Non-disjunction causes faulty cell division and produces three copies of the 21st chromosome instead of two.
Down syndrome is the most common birth defect in the United States and occurs in about 1 in every 800 infants. This birth defect does not have any treatments to cure the disease. This disease was discovered in 1866 and named after the physician who discovered it, John Langdon Down. There are three different types of Down syndrome, the most common being trisomy 21. Trisomy-21 is an extra copy of the 21st chromosome.
Down's Syndrome Down's syndrome is a genetic condition involving an extra chromosome, this change occurs around the time of conception. A person with Down's syndrome has forty-seven chromosomes instead of the usual forty-six. A relatively common genetic disorder, Down's strikes 1 out of 600 babies. In 95 percent of all cases, the disorder originates with the egg, not the sperm, and the only known risk factor is advanced maternal age-at age 35, a woman has 1 chance in 117 of having a baby with Down's; at 40, her odds are 1 in 34. (Graves, 1990) People with Down's syndrome all have a certain degree of learning disability .
There are three possible mutations to cause this inactivity. The most common cause is the deletion of the part of chromosome 15 that is inherited from the father, occurring in 70% of cases. In 25% of cases uniparental disomy (UPD) occurs and two copies of the chromosome are received from the father and none from the mother. 5% of patients diagnosed with Prader-Willi syndrome have an ‘imprinting mutation’. This is a form of translocation and means that the sequences of the genes on chromosome 15 are altered.
Down Syndrome in Children Down syndrome is one of the most common and easily recognized genetic disorders. It is caused by abnormal cell division that involves the 21st chromosome pair of the 23 pairs of chromosome found in all normal human cells. There are three types of these abnormalities, which are non-disjunction, translocation, and mosaicism. Ninety five percent of children born with Down syndrome are a non-disjunction type which is three rather than two chromosome 21s. About three to four percent of cases are because of translocation which is chromosome 21 detaches and attaches to another chromosome.
Down’s Syndrome is a common disorder due to an extra chromosome number; it is the most common cause of mental retardation that occurs in 1 in 1,000 babies in the United States. (Genetic Science Learning Center) There are three types of Down’s Syndrome: Trisomy 21, Translocation, and Mosaicism. Trisomy 21 is the most common type of Down’s Syndrome; it occurs in 95 percent of Down’s Syndrome cases. Trisomy 21 is a disorder in which a newborn receives an extra third chromosome-21, instead of the normal 2. The second type of Down’s Syndrome is Translocation; it occurs when only a small piece of the chromosome-21 is found on another chromosome.
Down syndrome is a genetic mutation caused by an error in cell division that results in an extra 21 chromosome. This is found on the long q arm of chromosome 21, and concludes in 47 chromosomes rather than the normal 46 chromosomes. The number of people born with down syndrome is increased if the mother carrying the child is older. More than 400,000 people in the United States have down syndrome, and the number grows daily. This disease is the most common of any genetic mutation as 1 in every 700 babies gets diagnosed with it at birth.