A human body consists of cells, most of which contain a center called a nucleus. Within these nuclei lies the material that contains the coding of our inherited characteristics. (Byrne, Cunningham & Sloper, 1988) This material is known as genes. Genes are composed of rod-like structures called chromosomes. Chromosomes are paired in all cells, and human cells are meant to have 23 pairs, an equal number from each parent. Down Syndrome is caused when some or all of an individuals’ cells has an extra full or partial copy of cell pair number 21.
(Byrne, Cunningham & Sloper, 1988) 95% of Down syndrome cases are caused by a particular abnormality called Trisomy 21. (Byrne, Cunningham & Sloper, 1988) This condition occurs when during conception, one of the parent cells’ 21-pair fail to separate, leading to development of cells with 47 individual chromosomes, rather than 46. (Byrne, Cunningham & Sloper, 1988) This error in replication is known as “nondisjunction”. (Byrne, Cunningham & Sloper, 1988) The two other forms of Down Syndrome are mosaicism, and translocation.
(Byrne, Cunningham & Sloper, 1988) Mosaicism occurs when nondisjunction occurs only in the initial stages of cell division, leading to a total cell structure consisting of cells that have 46 chromosomes, and some that have 47 chromosomes. (Byrne, Cunningham & Sloper, 1988) This form accounts for only 1-2% of the population of the disease. (Byrne, Cunningham & Sloper, 1988) The remaining form 3-4% of Down syndrome patients are victims of translocation. (Byrne, Cunningham & Sloper, 1988) This results when part of pair 21 breaks off during cell division and attaches itself to another pair, typically pair 14.
Causes: At this time, the causes of the nondisjunction are unknown. (Hurley, 1996) The only factor that has been definitively linked to the occurrence of Down Syndrome is the age of the mother. (Hurley, 1996) At the age of thirty-five, a mother has a 1-in-383 chance of producing a child with Down Syndrome. (Hurley, 1996) By age forty, that ration becomes 1-in-85. Surprisingly, though, most Down Syndrome babies are born to women below the age of thirty-five. (Hurley, 1996) This is a result of the much larger birth rate among younger mothers in general.
A small correlation between the probability of having a Down Syndrome baby and the incidence of having already had one can also be seen, but only about 1% increase in probability has been noted. (Hurley, 1996) The translocation form of Down syndrome has not been linked at all to maternal age. (Hurley, 1996) These cases arise sporadically, with no clear pattern to indicate causality. About one in three of these cases appear to have one or the other parent as the source of the translocation, which makes the risk for a second baby with the condition higher.
(Hurley, 1996) Symptomology: There are over fifty characteristics that will appear in Down syndrome patients. Each of these varies in severity, and the overall number of symptoms also varies. (Statford, 1980) Most Down syndrome patients have some common characteristics. One of these is short stature. (Statford, 1980) Down syndrome children grow more slowly than average and generally are below-average in adult height. (Statford, 1980) Another common characteristic of Down syndrome is a general weakness in the muscles known as hypotonia.
(Statford, 1980) This is particularly noticeable in the stomach, where the lack of tensile strength typically causes the appearance of a round belly. Younger patients also exhibit a thick neck with excess fat and skin, but this trait becomes less noticeable as the patient grows older. (Statford, 1980) Down Syndrome patients also typically have short and stocky arms and legs, and some have a wide gap between their first and second toes. A transverse palmar crease, or simian crease is also apparent on the hands of Down syndrome patients.
(Statford, 1980) This is located on both hands. There are also several facial features that are common among Down syndrome patients. (Statford, 1980) They generally present with small ears that are set low on the skull. They also typically have an irregularly shaped mouth and tongue. (Statford, 1980) In some cases, the tongue protrudes, and the soft palate is curved sharply upward. (Statford, 1980) The nasal bridge also has a pushed-in appearance in many such patients.
The irises of Down syndrome patients can contain buildups of tissue known as Brushfield spots, but these do not adversely affect vision. (Statford, 1980) Down syndrome patients typically have late-developing adult teeth that are often crooked. (Statford, 1980) Down syndrome patients also are prone to other medical conditions. The most common and well-known of these are cognitive disabilities. (Statford, 1980) Most patients with Down Syndrome have mild to moderate cognitive disabilities. Additionally, the Down Syndrome patient is prone to heart defects.
(Statford, 1980) This affects about ? of Down syndrome sufferers, and is typically diagnosed at birth. (Statford, 1980) Additionally, Down syndrome patients have increased instances of hypothyroidism, celiac disease, as well as vision, respiratory, hearing and dental issues. (Statford, 1980) Complications Patients with Down syndrome are statically far more likely to develop other significant health issues. (Pary, 2008) Down syndrome patients are more likely to develop leukemia in their youth than are the general population.
(Pary, 2008) They are also more susceptible to communicable diseases owing to defects in their immune systems. (Pary, 2008) Due to skeletal and other structural abnormalities common among Down Syndrome patients, they are more likely to suffer from sleep apnea than the general population. (Pary, 2008) They are also more prone to obesity than the general population. Although the average life span of a Down syndrome patient has increased greatly across the years, the life expectancy of the Down syndrome patients is upwards of fifty years.
(Hurley, 1996) In the 1920s, such patients could only be expected to live to be 10 years. (Hurley, 1996) Testing and Diagnosis Screening tests are now a common part of normal prenatal care. (Leshing, 2007) Down syndrome in the unborn can be detected in a number of different ways. In the first trimester of pregnancy, a two-part test can be administered to check for the risk of Down syndrome in the unborn child. (Leshing, 2007) The test has a 5% rate of false positives, however. (Leshing, 2007) The first part of this test is done by means of ultrasound.
Using this devise, the doctor measures a specific region of the neck of the fetus. This type of test is called a nuchal translucency screening test. (Leshing, 2007) The doctor is looking for an abnormal amount of fluid accumulation in this region; its presence is a precursor of Down syndrome. (Leshing, 2007) Blood tests on the mother are done in concert with the ultrasound. These check the mother’s blood for abnormal levels of pregnancy-associated plasma protein-A (PAPP-A) and a hormone known as human chorionic gonadotropin (HCG).
(Leshing, 2007) If these levels are outside a certain range, such a result can be indicative of problems with the fetus including Down syndrome. (Leshing, 2007) In the second trimester, a form of test known as the Quad test can check the mother’s blood for levels of four different pregnancy-related hormones. (Leshing, 2007) If any of these test indicate a problem, there are several definitive diagnostic tests that can be used to determine if a fetus is afflicted with Down Syndrome.
(Leshing, 2007) Amniocentesis is one such test. The doctor removes some of the amniotic fluid from the womb of the mother. (Leshing, 2007) This fluid contains cells from the fetus, which can then be examined to determined if they have the abnormal chromosomal development. (Leshing, 2007) A second such diagnostic test is Chorionic villus sampling, which consists of sampling from the placenta. From the placenta, cells from the fetus can be extracted and tested for chromosomal issues.
A final diagnostic test for Down syndrome Percutaneous umbilical blood sampling, (Leshing, 2007) which consists of a test of umbilical blood for fetal cells with chromosomal abnormality. (Leshing, 2007) This test carries a greater risk of miscarriage, so is generally only used if a speedy diagnosis is necessary. Life Style: Children and adults with Down syndrome can live relatively normal lives. (Appl, 1998) The cognitive disabilities that they typically have limit their achievement in the education, however they usually have limited ability to live and work on their own as adults.
(Appl, 1998) They generally are employed at unskilled jobs, typically in the service sector, where limited intellectual abilities are not considered necessary components. (Appl, 1998) Down syndrome children are also honored for their athletic abilities in the annual Special Olympics. (Appl, 1998) While not limited to children with this disease, the Special Olympics have become emblematic of the ability of Down Syndrome patients to participate in normal athletic competition, with little or no modification.
(Appl, 1998) The event is a major point of instance for advocates who classify Down syndrome patients as no different from the general population. (Appl, 1998) This viewpoint is the one most accepted by the general population. (Appl, 1998) Work Cited Appl, D. (1998) “Children with Down Syndrome: Implications for Adult-Child Interactions in Inclusive Settings” Childhood Education, 75 (1), 39. Byrne, E.. , Cunningham, C. & Sloper, P. (1988) Families and Their Children with Down’s Syndrome: One Feature in Common. New York: Routledge Publishing. Hurley, A. (1996)
“Identifying Psychiatric Disorders in Persons with Mental Retardation: A Model Illustrated by Depression in Down Syndrome” The Journal of Rehabilitation, 62 (1), 27. Leshing, L. (2007) “Prenatal Screening for Down Syndrome”. Retrieved June 5th, 2009 from Down Syndrome health issues website: http://www. ds-health. com/prenatal. htm Pary, R. (2008) “Aspects of Health Care of Adults with Down Syndrome” Mental Health Aspects of Developmental Disabilities, 11 (2), 61. Stratford, B. (1980) “Perception and Perceptual-Motor Processes in Children with Down’s Syndrome” Journal of Psychology, 100 (1), 139.