Uniparental Disomy Research Paper

time. There are a variety of milestones that include ways in which a child plays, learns,

Trisomy 18, or Edwards Syndrome as it is more commonly known, is a genetic disorder in which there is a problem with cell division called meiotic disjunction. This disease is commonly associated with the well known Downs Syndrome which is also known as Trisomy 21. A disease with an unnatural number of chromosomes are is called a aneuploidy. Edwards Syndrome occurs when a child is born with an extra #18 chromosome. This occurs in about 1 in 2500 pregnancies and 1 in 6000 births. There is a high mortality rate for Edwards Syndrome, half of all children who are carried to term will be stillborn. With the survivors less than 10% will live to be a year old, boys also having a higher mortality rate. (Trisomy 18 Foundation 2013). In this paper I will be addressing key components to Trisomy 18 and looking more closely at a few cases of “long living” survivors. Specifically history, symptoms, diagnosis, screening and treatment will be examined.

What happens to the body for this to happen? The body has 23 pairs of chromosome in our DNA.With XYY syndrome there is a extra y chromosome due to a split error in the sperm.Normally you have 46 chromosomes in your dna,but if the sperm cell has a error when it splits that can result with there being an extra y or x chromosome,the y chromosome either moves to a cell or leaves a cell before the cell splits in half and can cause there to be just a x chromosome or y chromosome which leads to a cell having to y chromosomes in one cell.That happens due to a cell spilt error.

Down syndrome is caused by having an extra chromosome on the twenty-first chromosomal pair. People with down syndrome have forty-seven pairs of chromosomes. There are three types of down syndrome and they are Trisomy 21, Translocation, and Mosaicism. Trisomy 21 is the most common type of down syndrome. It occurs when there are three rather than two, number 21 chromosomes present in every cell of the body. Trisomy 21 accounts for ninety-five percent of the down syndrome population. Translocation unlike Trisomy 21 only accounts for four percent of the down syndrome population. In this case, part of the twenty-first chromosome breaks off during cell divas and attaches itself to another chromosome, usually chromosome 14. Mosaicism is the rarest

Twins can be either monozygotic or dizygotic. Monozygotic or identical twins develop from one zygote, which splits and forms two embryos. They are natural clones of each other and are genetically identical. There are three types of monozygotic twins that can form, that depends on early development in the fertilized ovum or embryo splits. The first type of monozygotic twins have separate amnions and chorions. About one-third of identical twins separate before the trophoblast forms on the fifth day. The second type of identical twins that share one chorion and one amnion. This type of split happens about one percent in monozygotic twins, because the tissue splits after these structures are already developed. The third type of twins that are monozygotic, share a chorion and a different amnion. This type of split occurs in about two-thirds of identical twins. Identical twins occur in about thirty percent of births in the world, although not all twins survive long enough to be born. Dizygotic or fraternal twins occur when two sperm fertilize two separate eggs. This usually occurs when two eggs are released from the ovaries and are fertilized. Dizygotic twins normally run in females in the

Normally the baby is conceived with the usual 46 chromosomes. Then during cell division the chromosomes are divided into half the egg, and half the sperm, which end up with 23 chromosomes each. Although and error can occur during Monosomy is where the complete sex chromosome is missing, because of the fathers sperm or even the mothers egg. Mosaicism is when an error occurs in cell division in the early stages of fetal development and leads to cells in the body having two complete copies of the X chromosome, while others having only one copy of the X chromosome (Mayo Clinic, 2017). If there is a fully developed X chromosome and partial of a Y chromosome then the individual will develop as a female, with the risk of developing a type of cancer called gonadoblastoma. 45,X/46,XY affects a small percentage of girls with Turner's; small fragments of Y chromosome are in their cells, which can increase the risk of developing tumors, along with gonadoblastoma, in their internal sex organs. Deltion, ring chromosome, and isochromosome are different types of variations of Turner's Syndrome. Deletion is when the X chromosome is missing some of its genetic material. Ring chromosome is where there is two X chromosomes, but one is shaped like a circle with the ends joined. Along with isochromosome which is the X chromosome has two long arms instead of a long and short arm. (Turner's Syndrome Society,

Doctors refer this process as nondisjunction. During nondisjunction, when a pair of sex chromosomes fails to split during the egg (or sperm) formation, the egg that carries an additional X chromosomes will then combine with a normal sperm. As a result, the developed embryo will end up having three sex chromosomes, two X’s and one Y, instead of XY, the normal two. With the affected baby development, the extra chromosome will be copied to the rest of the cells. The chances of nondisjunction occurring in either the mother’s egg or the father’s sperm is equally. Half of the time, the error occurs in the egg development, and the remainder are due to errors in sperm

After karyotyping through amniocentesis, our team of obstetricians and cytogeneticists have identified a non-disjunction. This was done through taking a sample of amniotic fluid containing fetal skin cells and placing it in a laboratory dish with chemicals and hormones to allow the cells to divide rapidly. After a week, we applied colcemid, a drug that stops mitosis at the metaphase stage. Various other chemicals were then applied to swell the cells at the metaphase stage of mitosis and the cell was placed in a microscope slide to dry. Gimesya dye was then applied to identify the different chromosomes in the cell and a picture of the stained chromosomes was taken. The chromosomes were arranged by size, which were then analyzed.

Down syndrome is a congenital disorder arising from a chromosome defect, the chromosome causing the problems is Chromosome 21. Down syndrome current affect about 1 in 600-800 live births in the United States. There are about 400,000 Americans that have Down syndrome, with approximately 6,000 babies are born with this disorder each year. The disorder is thought to form during gametogenesis, during fertilization, or soon after fertilization (Daniilidis, et al. 2015). Fertilization occurs when the sperm binds to zona pellucida, then the sperm undergoes acrosome reactions which will lyses a hole in zona pellucida, and then the sperm and egg membrane fuse. Once the membranes fuse, the sperms genetic material gets released and gets combined with the egg’s chromosomes, thus resulting in a 46 chromosome fertilized egg. This is the mostly likely phase in which Down syndrome gets formed, since it is caused by a mistake in cell division during the development of the egg, sperm or embryo. The mother or the father can be the origin in which the extra partial or full chromosomes come from, but approximately only 5% have been traced to the father. Maternal age is the only risk factor that has been linked to an increased chance of Down syndrome. Down syndrome is not inherited, but 4% of translocation Down syndrome is inherited (Mayo Clinic Staff).

When observing the female body, one can see that she has two chromosomes. A normal female has 46 chromosomes in totality. These chromosomes typically are two pairs of X's or one pair of Y and X chromosomes. According to the U.S. National Library of Medicine, a chromosome is defined as “The DNA molecule packaged into thread-like structures.” These chromosomes are located in the nucleus of each cell. Turner syndrome occurs when an X chromosome is completely or partially lost. When a male and female procreate, a mistake occurs with the formation of the egg and sperm. This leads to a cell withholding a sex chromosome to the embryo and thus, one chromosome is nonexistent. An error can take place with either the mother's eggs or the father's sperm.

     Mosaic Trisomy 21 happens when an egg or sperm come in with an extra copy of chromosome 21, then,

Chromosome mutations or abnormalities involve the rearrangement of whole blocks of genes. They usually occur during meiosis

Down syndrome is usually caused by an error in cell division called non-disjunction. However, two other minor types of chromosomal abnormalities, mosaicism and translocation, are also causes of Down syndrome. Regardless of the type of Down syndrome that a person may have, all people with Down syndrome have an extra, critical portion of the number

Chromosomal abnormalities caused by errors at the number of chromosomal pairing and structural damages during cell division (Mahdieh and Rabbani, 2013). Examples of these abnormalities are duplication, inversion, insertion, deletion, and translocation, ring shaped chromosome, and breakage of part of chromosome structure (Mahdieh and Rabbani, 2013).

Independent assortment occurs during meiosis when both maternal and paternal homologous pairs separate independently, distributing chromatids from each parent to the gametes independent of each other (Mendel, 1865). As maternal and paternal chromosomes carry different genetic information, independent assortment produces different possible combinations of chromosome pairs. Recombination is a feature of independent assortment, producing further new gene combinations by breaking and recombining DNA fragments. Following this is crossing over; the exchange of genetic material during meiosis between non sister