The Origin of Molar Pregnancies, the Consequences on Embryo Development and Molecular Techniques - Coursework Example

Introduction A molar pregnancy is said to take place when the fertilization of the egg by the sperm is abnormal leading to development of abnormal cells or some clusters that consist of water filled sacs that are found inside the womb. This condition falls under other group of conditions that are referred to as gestational trophoblastic tumors. Research has shown that most molar pregnancies are not cancerous. This pregnancy is known to spread beyond the womb in most women. However, this condition is still curable. A molar pregnancy is a missed miscarriage because the pregnancy is not viable and it was not immediately expelled. The two types of molar pregnancies are the complete mole and the partial mole. Origin of molar pregnancies. The origin of molar pregnancies can be traced from the time when there are problems especially with the genetic information of the chromosomes that are found in the egg that is fertilized at conception. The obvious result is that the egg may build up into a growth that has no embryo. In a standard pregnancy, the fertilized egg has 23 chromosomes, which are from the father, and another 23 from the mother. With a molar pregnancy, this usually not the case. In complete molar pregnancies, the fertilized egg has two copies of chromosomes that originate from the father and no chromosomes come from the mother. It is clear that from this case, there will be no embryo, amniotic sac, and the usual placental tissue. In its place, the placenta develops a mass of cysts that resemble a bunch of grapes. In addition to that, in a good number of partial molar pregnancies, the egg which has been fertilized, contains a normal set of chromosomes that come from the mother and another two sets from the father. As a result, there will be 69 chromosomes instead of the usual count of 46. This mainly takes place when the chromosomes that originate from the sperm are replicated or when there is an occurrence of two sperms fertilizing the same egg. However, in a partial molar pregnancy there is the presence of the normal tissue from the placenta that is alongside the cluster of the abnormal tissue. Thus, the embryo may start to develop into some fetal tissue or fetus. In spite of this development, the fetus is very abnormal and may not survive in most cases. From genetics, molar pregnancies are the premalignant forms that may also consist of unusual but hostile malignancies of placental site and tumors. luckily, because there is no any other indication of further treatment, the women that experience simple molar pregnancies have a reason to be assured that they are not experiencing cancer and that they will require some close monitoring. The genetic events that take place in a normal conception as well as in partial and complete molar pregnancies, may be represented in a diagram as shown below. In a normal conception, 23 chromosomes originate from the mother and another 23 from the father, whereas in complete molar pregnancies the genetic material is all of the male origin. This is because of the loss of all the maternal chromosomes. Most molar pregnancies are not cancerous and are confined in the uterus. In this type of mole, the placental tissue, which is abnormal, consists of villi and some bunches of tissues that are swollen with fluid. A more destructive tumor that is associated with a molar pregnancy is known as the chorioadenoma destruens. This mole consists of many villi, which may grow through the uterus wall muscle wall. These moles rarely cause bleeding. Very few cases have shown the invasive mole spreading to tissues that are located in the area outside the uterus. From research, it is clear that all the forms of molar pregnancies are found frequently in women from Asia or Africa origin. In the United States, these pregnancies are rare as only one incident occurs in every 1,250 pregnancies. Some of the things that may increase a person’s risk of getting a molar pregnancy include age where women above 35 years have a high risk of experiencing it, if you have had a history of the pregnancy especially if you have had one before, if you experience miscarriage and having a diet that that is low in carotene. Carotene has vitamin A. women who lack this vitamin are likely to have a higher rate of having a molar pregnancy. Consequences of molar pregnancies on embryo development. Molar can have various effects on the development of the fetus. The two types of molar pregnancies that is complete molar molar pregnancy and the partial molar pregnancy will have different effects on the growth of the fetus. In a complete molar pregnancy, the sperm that originates from the father is used to fertilize an empty egg that has got no genetic material that is supposed to come from the mother. There are other instances where two sperms are used to fertilize one egg. Since there is no egg in this process. It is not possible for the embryo to develop. Instead of the embryo, a big mass of abnormal tissue is formed. This abnormal tissue is only seen by an ultrasound scan. Fertilization involves the fusion of the male and female gametes. But in this instance there is no ovary. The presence of the female egg that has got no genetic material, shows there will be no fetus development in the process. In addition to that, partial molar pregnancy has also its own effect on the development of the fetus. In this case, two sperms fertilize a normal egg. This gives the embryo a big number of chromosomes. The fetus may begin to develop as may be seen if a scan is made. Unfortunately the fetus is malformed and it may not survive and develop into a baby. The numerous number of the male chromosomes are the ones that have got a negative effect on the development of the fetus. In order for the fetus to develop into a child the number of chromosomes from both the male and female must be balanced. Molecular techniques that are used to detect molar pregnancy. Ultrasonography is one of the techniques that is used to detect molar pregnancy. The introduction of this method has made the diagnosis much earlier than before. Apart from providing information about the type of molar pregnancy, ultrasound determines the association of the endometrial cavity, analyses the risk that can result from uterine perforation, and also detects the lutein cysts and some vaginal metastases. The diffuse and intense swelling of the chorionic villi is a characteristic pattern on ultrasound. This swelling has got several holes that are found inside the placenta with the absence of the fetus. However, as the pattern is observed in women, who have experienced missed abortion and uterine fibroids, the ultrasound diagnosis only is not that specific. When you combine ultrasound with the elevated hCG, there is an absence of the fetal heart beat. As a result, molar pregnancy is the most likely diagnosis. Flow cytometry is another common method. This technique separates a partial mole from a complete mole by simple demonstration of triploidy. The conventional karyotyping is an accurate chromosomal method for enumeration that may be used in confirming the presence or absence of triploidy in a partial mole. If you want to determine the number of some haploid chromosome sets, you may use interface fish. However, these methods do not differentiate between a diploid complete mole from a non-molar gestation. The analysis of a chromosome known as pericentromeric may used in identifying the parental basis of the chromosomes. DNA geneotyping gives the best measurement of all genetic variations between all the members of a given species and it can therefore be used to ascertain the parental source of any genomic haploid sets. A number of molecular methods have been examined including DNA restriction fragment , enzyme polymorphism and the single nucleotide polymorphism. Not a while ago, the short tandem polymorphism has emerged as the most detailed and specific method for identifying molar pregnancies. Its effectiveness in diagnostic power has been enhanced by several studies by researchers. The diagnosis of molar pregnancy may also include using pathologic investigation of curettage tissue. Histologic analysis can be quite challenging because the diagnosis of the hydatidiform takes place during the earlier stages during the gestation period. The difference between the partial mole, hydropic abortus and the complete mole can be differentiated by the means of cytogenetic analysis. In addition to that, immunohistochemical analysis can be used to confirm the diagnosis of a molar pregnancy. For instance, it can be used to distinguish between a complete and a partial molar pregnancy. With this method, the protein is imprinted paternally and expressed maternally. As a result, the villous that lack maternal chromosomes, will be stained negatively whereas the rest will stain positive. References http://www.myvmc.com/diseases/molar-pregnancy-gestational-trophoblastic-disease-gtd/#How_is_it_diagnosed http://www.webmd.com/baby/tc/molar-pregnancy-topic-overview http://www.molarpregnancy.net/ http://www.bandbacktogether.com/Molar-Pregnancy-Resources/ http://omicsonline.org/molecular-diagnosis-of-hydatidiform-moles-is-ready-for-primetime-2161-0681.1000e105.php?aid=4048 https://www.inkling.com/read/principles-practice-gynecologic-oncology-6th/chapter-27/management-of-molar-pregnancy http://www.babycentre.co.uk/a1015048/molar-pregnancy http://humrep.oxfordjournals.org/content/14/4/1122.long Read More