Trisomy is a cell that has three copies of one chromosome instead of having the normal two copies. Trisomy 21 is the congenital disorder better known as Down syndrome. This occurs when each cell has three copies of chromosome twenty-one rather than having a normal pair. Nondisjunction is "an error in which homologous chromosomes or sister chromatids fail to separate normally during meiosis or mitosis" (Huether,McCance pp.42). Therefore, nondisjunction is a common cause of Down syndrome. Scientists have made the discovery that Down syndrome is caused by an extra chromosome, but the cause of why that occurs is unknown. The main risk for having a child with Down syndrome is maternal age. After the mother reaches the age of 35, the risk of
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A triple screen test is an example of blood work the mother may have tested during her pregnancy. This happens between the 15th to 20th week of pregnancy. However, it is not uncommon to have false positive and false negative results with this screening test. The mother needs to remember that this is not a diagnostic test, and abnormal results indicate the need for further diagnostic testing. In addition to blood work, an ultrasound is another screening test used during pregnancy. The ultrasound checks to see if extra fluid is behind the baby's neck. Extra fluid around the neck could suggest chromosomal abnormalities. If the screening tests show anything abnormal, diagnostic testing will be the next step to further evaluate the screening results. For example, chorionic villus sampling is a diagnostic test that occurs around 10 -12 weeks. CVS examines a portion of the placenta to inspect for chromosomal problems. An additional diagnostic test, amniocentesis, checks the cells in the amniotic fluid for chromosomal defects around 15-18 weeks. After the mother gives birth, physical characteristics and a blood test taken from the newborn can diagnose Down syndrome. Low set ears, a tongue that sticks out, flat nasal bridge, and eyes that slant upward are some distinguishing facial features. A karoytype test makes the official diagnosis of Down syndrome. This test looks at the chromosomes and checks the total
A triple screen test is an example of blood work the mother may have tested during her pregnancy. This happens between the 15th to 20th week of pregnancy. However, it is not uncommon to have false positive and false negative results with this screening test. The mother needs to remember that this is not a diagnostic test, and abnormal results indicate the need for further diagnostic testing. In addition to blood work, an ultrasound is another screening test used during pregnancy. The ultrasound checks to see if extra fluid is behind the baby's neck. Extra fluid around the neck could suggest chromosomal abnormalities. If the screening tests show anything abnormal, diagnostic testing will be the next step to further evaluate the screening results. For example, chorionic villus sampling is a diagnostic test that occurs around 10 -12 weeks. CVS examines a portion of the placenta to inspect for chromosomal problems. An additional diagnostic test, amniocentesis, checks the cells in the amniotic fluid for chromosomal defects around 15-18 weeks. After the mother gives birth, physical characteristics and a blood test taken from the newborn can diagnose Down syndrome. Low set ears, a tongue that sticks out, flat nasal bridge, and eyes that slant upward are some distinguishing facial features. A karoytype test makes the official diagnosis of Down syndrome. This test looks at the chromosomes and checks the total