Prenatal Screening (Prenatal Testing) in Clinical Chemistry Labs - Research Paper Example

? Prenatal screening Prenatal Screening Prenatal testing provides information concerning the health of the baby before the baby is born. Some of the routine tests performed on a pregnant mother help to monitor her health (Otano, 2007). During the first visit, the health care provider tests a number of aspects including the mother’s blood, signs of infection, and whether the mother is immunized against chicken box and rubella. In particular, prenatal test help to identify treatable health complications, which can potentially harm the health of the unborn child. These tests are also important since they can help to identify the characteristics of the unborn child including size, age, and the placenta in the uterus. Prenatal tests help to identify the chances that the unborn child exhibits certain genetic, congenital and chromosomal disorders as well as fetal abnormalities inclusive of some complication of the heart (Otano, 2007). Throughout the period of pregnancy, the health provider normally suggests a number of tests including screening test for Down syndrome, gestational diabetes and HIV (Mayo Clinic, 2013). Disorders of prenatal testing include dominant gene disorders. When one of the parents suffers from the dominant gene disorder, then there is a 50 percent likelihood of the baby to inherit such genes and develop the disorder. Achondroplasiais is a form of short-limbed dwarfism that literally means "without cartilage formation." Cartilage is a tough but flexible tissue that makes up much of the skeleton during early development. However, in achondroplasia the problem is not in forming cartilage but in converting it to bone (a process called ossification), particularly in the long bones of the arms and legs. The disease is inheritable from an affected parent and in most cases occurs with no family history (Cunningham, 2010). The testing procedure entails direct mutation analysis, which involves analysis of samples using PCR assay. Polymerase chain reaction (PCR) refers to a technique used to amplify and copy small DNA segment. Once the DNA are amplified, they are then used in clinical labs in process such as detection of viruses and bacteria and diagnosis of genetic disorders. In order to amplify DNA segments, the sample is heated for DNA denaturing and then the tag polymerase synthesizes and builds two new DNA strands Huntington’s disease is a brain disorder, which affects an individual ability to think, talk, and move. It destroys cells located in the basal ganglia brain section that controls emotion, movement, and cognitive ability. It is caused by mutation of genes on chromosome 4. Clinical methods used in clinical diagnosis include chronic villus sampling, amniocenteses, and PCR. Examples of recessive gene disorders include Cystic Fibrosis and Tay-Sach’s disease. Cystic Fibrosis is a genetic disorder, which affects the digestive system and the lungs increasing vulnerability to lung infections. It disrupts the normal functioning of epithelial cells and the digestive system. Amniocenteses and chronic villus sampling diagnose it. Tay- Sachs diseases is a progressive fatal genetic disorder, which affect the nerve cell in the brain. It occurs when neither of the parent HEXA genes works properly due to mutation. Amniocentesis is normally used where a blood sample measures HEXA levels. . Other disorders diagnosed in clinical chemistry labs include X- Linked disorders. They refer to disorder determined by genes attached on the X- chromosome. Both the X and Y-chromosomes determines the sex of a child. These disorders are most common among boys because the pair of the sex chromosome in male has only one X chromosome and the other is the Y-chromosome. When the gene disease is present on the X chromosome, then the X- linked disease manifests because of the absence of a paired gene to override the disease gene. Hemophilia is an example of the linked disorder, which prevents blood clotting. It the ability of blood from coagulating When blood vessels are injured, a temporary scab fails to form, and the absence of coagulation factors inhibits fibrin formation, a necessary entity for blood clotting. The methods used are PCR and CVS Chromosomal disorders occur when there is an abnormality in the structure or number of chromosomes, which have the genetic material (Children Health, 2013). Although most chromosomal disorders result from a random error in the genetic composition of the sperm or egg, some are inherited. Amniocentesis is used to detect chromosomal disorder. A sample amniotic fluid is taken through the uterine or abdominal wall, using a needle and tested for the disorder. Maternal Blood Screening tests tube defects and Down syndrome. The test examines the level of the pregnancy hormones, human chorionic gonadotropin, and estriol, which at times makes the test to be referred as triple screen. These hormones play a key role to pregnancy including stimulating thickening of the uterine wall, development of sexual characteristics and aids in the nutrition of the fetus. Hormonal levels are determined by amniocenteses where a sample of amniotic fluid taken and analyzed. Sometimes the test is performed along with blood work and ultrasound in the first trimester thus increasing accuracy. Chorionic Villus Sampling is a test done during early pregnancy that can find certain problems with the fetus. It is generally done when either the mother or the father has a disease that runs in the family, a genetic disorder. Chorionic Villi are the tiny finger like units, which constitute the placenta. They have the same genetic makeup and chromosomes as the fetus (Cunningham, 2010). As an alternative to amniocentesis, it removes some of the chorionic villi while testing for chromosomal abnormalities. This method is advantageous since it is performed early in time and allows expectant parents to receive adequate counseling and make informed decision. The test is done between 10 to 12 weeks. It is carried out using transcervical, which uses ultrasound as a guide. A thin tube is passed through the vagina into the cervix and a gentle suction removes a sample tissue from the chorionic villi. Some women have reported of cramping upon the removal. In the transabdominal method, a needle is inserted through the abdominal wall under guidance of ultrasound and sample of chorionic vilii removed. Amniocentesisis used to detect inheritable metabolic disorders, Down syndrome and chromosomal abnormalities and structural defects. In the late stages of pregnancy, the test reveals if the lungs of the unborn child are strong to allow for normal breathing (Otano, 2007). This helps in decision making regarding to inducing labor or preventing labor. This test shows other birth defects such as the palate, cleft clip and hear disorders. This test is more accurate though only certain disorders are detectable. It poses low risks of uterine infection. It is performed between 15 to 20 weeks. With the guidance of ultrasound, the doctors insert a needle through the abdominal wall into the uterus and remove a sample of amniotic fluid. Cells in a sample fluid are cultured and analyzed. Results are availed within 1 to 2 weeks. However, test of lung maturity are availed within hours. Newer assay methods being used in clinical chemistry labs include Fluorescence In Situ Hybridization (FISH) and Polymerase Chain Reaction (PCR). FISH is a useful method for detecting aneuploid condition, monosomies, and trisomies. Fresh cell are employed though the method could be used to fixed tissues, which are stored in paraffin blocks. However, using paraffin blocks consumes time and even the final interpretation can be much difficult. Using FISH on paraffin implies that the archival tissues are examined. Fish is a cytogenetic technique used to detect and localize the absence or presence of specific DNA sequences on chromosomes. Fluorescent probes, which bid to only those parts of the chromosome to those that show a high degree of sequence complementarily, are used. In essence, fluorescent microscopy locates where the fluorescent tube is bound on the chromosomes. FISH method locates specific features in DNA to be used in medicine, genetic counseling, and species identification. It also detects and localizes specific RNA targets in cells, tissue samples, and circulating tumor cell. Polymerase chain reaction (PCR) refers to a technique used to amplify and copy small DNA segments. Once the DNA are amplified, they are then used in clinical labs in process such as detection of viruses and bacteria and diagnosis of genetic disorders. In order to amplify DNA segments, the sample is heated for DNA denaturing and then the tag polymerase synthesizes and builds two new DNA strands. The process causes DNA duplication with each molecule containing one new and one old DNA strand. After, this the new strands are used to create new copies and the process continue. This cycle us repeated to over 30 to 40 times leading to billion exact copies of the original DNA segment. Alpha-fetoprotein (AFP) AFP is a protein produced by the liver and the yolk sac of the developing baby during pregnancy (Otano, 2007). Levels of AFP decrease after birth and it has no known functions in adults. Tests can be performed to determine the amounts of AFP in the blood of the pregnant mother. A blood sample is used and it has no special preparation. The test is important to diagnose liver disorders, problems in the baby and monitor certain cancers. During pregnancy AFP test is carried out along with amniocentesis in helping The major risk of prenatal testing includes termination of pregnancy, as well as psychological and emotional risks (Gates, 2004). The physical risks related to prenatal testing are very small more particularly for those tests that need blood samples. Pregnant women under such tests have reported of physical discomfort including cramping. In essence, the procedures and method used in prenatal testing have a small but real risk of terminating pregnancy since they use a small sample of tissue or amniotic fluid from the fetus. However many of the risks relate to the social, financial and emotional risks of the test results. Most of the pregnant women who have undergone such testing may fell depressed, angry, guilt or anxious about the results. This paper has discussed the concepts of prenatal screening. As earlier shown, prenatal testing, gives information concerning health of the baby before she is born. Besides, some of the routine tests for performed on a pregnant mother help to check her health. This test are preformed throughout the pregnancy of the mother. Besides this test helps to identify various disorders detected by prenatal testing including dominant gene disorders such as Achondroplasia and the hunting disease, Recessive gene disorders such as cystic fibrosis and Tay-Sachs disease, X –linked disorders such as Hemophilia and Chromosomal disorders such as Down’s syndrome (Pincus,2006). As already shown different diagnostic methods are in place including FISH, Amniocentesis, and Maternal blood sampling Alpha-fetoprotein (AFP) among others. However, they are risks associated including the loss of pregnancy and emotional and psychological risks. References Children Health. (2013). Understanding Down Syndrome Diagnosis and Treatment, Retrieved on December 9 2013 from http://children.webmd.com/understanding-down-syndrome-treatment Cunningham F. G, (2010). Prenatal diagnosis and fetal therapy. In: Cunningham FG, Leveno KL, Bloom SL, et al, eds. Williams Obstetrics. New York, NY: McGraw-Hill Gates, E A (2004), communication Risk in Prenatal Genetic Testing, Journal of midwifery and women health, Retrieved on December 9 2013 from http://www.medscape.com/viewarticle/478290 Otano L. (2007). Prenatal genetic diagnosis. In: Gabbe SG. Obstetrics: Normal and Problem Pregnancies. Philadelphia, Pa: Elsevier Churchill Livingstone: Pincus, L (2006). Diagnosis and management of cancer using serologic tumor markers. In: McPherson, R. A. Henry's Clinical Diagnosis and Management by Laboratory Philadelphia, Pa: Saunders Elsevier Mayo Clinic (2013).Prenatal Testing: Is it right for You, Retrieved on December 9 2013 from http://www.mayoclinic.com/health/prenatal-testing/PR00014 Read More