Down syndrome In 1866, an English doctor named John Langdon Haydon Down described a certain type of

Embryonic tissue that was removed is first tested for genetic abnormalities. This is done so that the healthiest embryos are frozen and implanted. Dr. Timothy Yeko, a medical director of the assisted reproductive technology program at the Reproductive Medicine Group in Tampa, talked about the genetic testing, “ Most of our patients now choose to have this genetic testing, which has come into widespread use in the past year or so. By doing this , the miscarriage rate has dropped by 50 percent because the genetically abnormal embryos are the ones that end in miscarriage.”

. Down syndrome is not a disease that someone catches and is not caused by difficulties during the pregnancy, it is a genetic condition. This condition is caused by the presence of an extra chromosome in the body’s cells and causes a redundant amount of proteins to be formed. All cells of the body derive from a single cell formed by the fusion of a father’s sperm and a mother’s egg. Each cell carries a nucleus full of genetic material known as genes. These genes are inherited from both the mother and father. Each cell normally contains 46 pairs of chromosomes. 23 chromosomes come from one parent and 23 from the other, hence the 46 pairs. When it comes to children with down syndrome, one of the chromosomes does not separate properly and so the

Procedures such as amniocentesis and chorionic villus sampling (CVS) represent the standard diagnostic methods used by clinicians to screen fetuses for abnormalities or genetic disease such as Down syndrome. In amniocentesis, a needle is inserted into the amniotic sac of the mother and a small sample of amniotic fluid is obtained. Fetal tissue is contained within the amniotic fluid and is subsequently analyzed genetically and cytogenetically for abnormalities. In the case of CVS, a sample of placental tissue is obtained through the mother’s cervix for downstream genetic analysis as in the case of amniocentesis (CDC,

Down syndrome is a genetic disorder that numerous individuals around the world suffer from; it is an intellectual disability that is caused by having one too many chromosome 21 copies, trisomy 21. The average person has two copies of chromosome 21 in each cell, whereas, an individual with Down syndrome has an extra copy of chromosome 21. This happens when either the sperm or egg cell undergoes atypical cell division during development. In the United States, there are approximately 400,000 individuals who have been diagnosed with Down syndrome, according to the last census in 2012 (National Down Syndrome Society).

The first way that prenatal testing can be done is through something called a prenatal diagnostic test. "In general, it is the diagnostic procedures, such as amniocentesis and chorionic villus sampling, that people think of when they hear the term prenatal testing," (Press 1). Amniocentesis is when doctors take a sample of the fluid that surrounds the baby in the uterus to determine certain genetic disorders or chromosomal abnormalities. Chorionic villus sampling is when doctors take cells from projections on the placenta to also discover any genetic disorders or chromosomal abnormalities. These processes are considered "invasive" because they are putting objects that could potentially hurt the baby into the protective area surrounding the baby. These ways of prenatal testing come with a very negative feeling because they could possibly injure the baby, and the word invasive is attached to a very negative connotation. However, these options can find more abnormalities and diseases than non-invasive prenatal testing. "NIPT accurately diagnoses Down's syndrome, Edward's syndrome, Patau syndrome, Turner's syndrome, and numerical chromosome aberration and cannot detect other chromosomal anomalies," (Ryu & Kim 1). Even though this is true, NIPT is still a very beneficial option to the mother and unborn child. NIPT usually uses a DNA sample to determine chromosomal abnormalities that could lead to things such as Down's syndrome. The procedure is done by the doctors taking a sample of the mother's blood to determine what types of diseases and disabilities the baby will have. Many people like this type of prenatal testing because it is not detrimental to the baby, or mother's health. "Studies investigating the acceptability of NIPT suggest that pregnant women find it preferable because the standard screening is associated with more uncertain results and

Amniocentisis is the most common prenatal test performed today (Morris, 1993). While the test is not totally risk free, estimated fetal loss due to amniocentesis is less than 0.5 percent (O'Connor, 1989). This procedure involves the extraction of a small amount of fluid surrounding the developing fetus. Within this fluid are cells which contain the genetic information of the fetus. Upon analysis of this fluid, the determination of the sex as well as the location of genetic abnormality causing genes can be identified.

by sampling the amniotic fluid, which contains cells and chemicals which are fetal in origin.”(4) This

The biopsied cells are transferred to a small tube for genetic testing. Due to the time taken to perform the genetic testing, the embryos must be frozen after the

The study of the DNA of human embryos was possible at the time when in vitro fertilization began to be practiced. In vitro fertilization (IVF) is the process of forming a human embryo outside the womb. The process involves extracting several eggs from a woman’s body and then fertilizing them in a laboratory. A couple days after fertilization, genetic tests can be applied on a cell that is removed from the embryo. The DNA testing process is called preimplantation genetic diagnosis (PGD) and usually triggers the diagnosis of the embryos with genetic abnormalities but can also identify other genetic traits of the future progenitor such as sex, athletic ability, special talent, and certain physical appearance.

Beth can also go through a procedure known as amniocentesis. Amniocentesis where they insert a needle into the mothers’ abdomen and retrieve amniotic fluid. With the amniotic fluid they can do testing to determine the genotype of the fetus Finally, she could also do chorionic villus sampling or CVS. This test is normally performed in the beginning of pregnancies. A needle is inserted into the vagina through the uterus to obtain a sample of cells from the placenta. The sample is then again sent to a lab to be tested. With both amniocentesis and CVS, they can determine over 200 genetic disorders. With both procedures, there is a risk of miscarriage, but is it extremely

There are three ways that a mother can be tested during pregnancy to see if their child will have Down syndrome. One is amniocentesis, which is the removal and analysis of a small sample of fetal cells from the amniotic fluid. Amniocentesis can not be done until the 14-18th week of pregnancy and with this process there is a lower risk of miscarriage than with the other two processes. Another process is chorionic villus sampling (CVS), which is the extraction of a tiny amount of fetal tissue at 9 to 11 weeks of pregnancy. The tissue is then tested for the presence of extra material from chromosome 21. Chorionic villus sampling has a 1-2% chance of the mother having a miscarriage. The last process is percutaneous umbilical blood sampling (PUBS), which is the most accurate method used to confirm the results of CVS or amniocentesis. During PUBS the tissue is tested for the presence of extra material from chromosome 21. PUBS cannot be done until the 18-22nd week and it carries a high risk of the mother having a miscarriage.

The existence of foetal DNA in maternal plasma was first discovered in 1997 which provided the opportunity to develop a non-invasive method to detect foetal genetic abnormality. It have been demonstrated that using real time PCR foetal DNA can be detected

If eggs are not being obtained from donation, the prospective mother is given drugs with the purpose of 'controlled ovarian hyperstimulation ' - the ovaries are caused to release a larger quantity of eggs, on demand. For a period of one to two weeks, ultrasound is used to observe the development of immature egg cells. When ready for extraction, the woman is put under sedation and a needle is used to remove the eggs. After a few hours of allowing the eggs to mature, the polar body of an egg (result of uneven cell division, would eventually dissolve) can be taken for testing. However, this sample contains only the mother 's DNA. If the objective is to test the whole DNA of the potential child, or to account for the father 's contribution, the eggs are then fertilised in vitro (in the lab), and a biopsy (typically three days after fertilisation) of the embryo is then performed, using a cell produced from the cell division.

The next technique routinely performed for prenatal diagnosis is amniocentesis. A long needle is inserted into the mother’s uterus to withdraw a sample of amniotic fluid containing cells shed by the fetus. The cells are cultured and analyzed for chromosome abnormalities. Despite the lengthy time in obtaining results because the cells need to be cultured, this method has become widely accepted as a safe and accurate way to determine genetic disorders.

Typically, the nucleus of each cell stores forty-six chromosomes. Half of these chromosomes derive from each parent cell. However, in those with Down syndrome, the cells contain forty-seven chromosomes. Researchers’ knowledge of the etiology of Down syndrome has grown since it was first described in 1866 by John Langon Down (National Down Syndrome Society, 2012). According to the National Down Syndrome Association (2012), 95% of the Down syndrome cases are caused by a fault in cell division. Although it is clear that this disorder occurs because of an alteration during cell division, the cause as to why this occurs is unknown. However, the pathogenesis of this disorder is clear. The pathogenesis of this disorder begins with nondisjunction during meiosis, which is failure of the chromosomes to separate. Today, it is known that there