Develop a response to this posting. Ensure you have answered all parts of the po
ID: 253874 • Letter: D
Question
Develop a response to this posting. Ensure you have answered all parts of the posting completely. Complete this assignment using complete sentences in a paragraph format, and be sure to check your spelling when complete.
It is now possible to have human embryos produced via in vitro (test tube) fertilization (IVF) tested for many different genetic diseases. The technique used to do this is called “pre-implantation genetic diagnosis” (PIGD). It is also possible for sperm/egg donor banks to carry out a fertilization event on paper before it is done in vitro. Discuss a genetic disease which can be diagnosed and may be a good candidate to be diagnosed early and avoided using the techniques listed above. Include a reference in your post.
Weigh in on the topic of PIGD in conjunction with IVF pointing out what you think are the pros and cons of this developing and ever-improving technology.
Respond to Others: Read the postings of your classmates and comment on at least one other student's response. Do you agree with his/her interpretation? Why? Why not?
Explanation / Answer
Pre-implantation genetic diagnosis ( PIGD) is a technique used to do genetic profiling of embryos before implantating them , and at times the genetic profiling of oocytes before fertilization. It is a similar procedure like prenatal diagnosis. When this method is used to screen a specific genetic disease, it helps in avoiding selective pregnancy termination , because the method highly ensures that the baby will be free from the disease which isbeing tested. In this technique usually embryos are obtained by blastomere or blastocyst biopsy. Biopsy is done around 5 or 6 th day of development.
PiGD is most frequently used to diagnose autosomal recessive disorders like cystic fibrosis, Beta-thalassemia, sickle cell disease and spinal muscular atrophy type 1. and for the most common dominant diseases like myotonic dystrophy and Huntington's disease.
Huntington's disease (HD), is an inherited disorder , which occurs due to death of brain cells. Symptoms of this disease are usually related to mood or mental abilities. There is a general lack of coordination and an unsteady gait usually found in the patient. when the disease advances, there is uncoordinated, jerky body movements occurs and the physical abilities gradually worsens and person declines to dementia.
HD is inherited from a person's parents, only 10% of cases occurs due to a new mutation.The disease is caused by an autosomal dominant mutation in either of the individual's two copies of a gene called Huntingtin.This means a child of an affected person has a 50% chance of inheriting the disease. The Huntingtin gene gives the genetic information of a protein that is also called "huntingtin". The expansion of CAG (cytosine-adenine-guanine) triplet repeats in the gene coding for the Huntingtin protein leads to an abnormal protein, this protein gradually damages cells in the brain. Diagnosis is by genetic testing, can prevent the disease ,there is no cure for the disease.
Embryos produced by in vitro fertilization can be genetically tested for HD using preimplantation genetic diagnosis (PIGD). In this technique, one or two cells are extracted from a 4- to 8-cell embryo and then tested for the genetic abnormality,this test can access whether embryo is affected with HD genesor not and decided to implant or not, as a result the offspring will not inherit the disease. Preimplantation genetic diagnosis allows people who are at risk to have HD-free offspring without revealing their own parental genotype, giving no information about whether they themselves are destined to develop HD. Also testing, the embryos' DNA and comparing with that of the parents and grandparents also helps in avoiding inheritance of the chromosomal region containing the HD gene from the affected grandparent. In non-disclosure testing, only disease-free embryos are replaced in the uterus but the parental genotype and parental risk for HD is not disclosed.
Advantages of PIGD:-
PIGD can test for more than 100 different genetic conditions.The procedure is done before implantation, as a result it allows the couple to decide if they wish to continue with the pregnancy.
PIGD allows to detect whether embryo has abnormal chromosome number , or it tests embryo is aneuploid or not .
If there is genetic disorder in family it helps in detecting whethere the offspring carries the disorder or not.
Disadvantages of PIGD:-
PIGD helps to reduce the chance of conceiving a child with a genetic disorder,but it is not 100% assured so, further testing is required during pregnancy to conclude if a genetic factor is still possible.
A risk of PIGD is it can damage the embryo during the biopsy procedure (leading to the destruction of whole embryo).
Another risk is during cryopreservation , when embryo is stored in a frozen state and when they are latter thawed and brought to normal condition , it is seen that about 20% of embryo do not survive.
It is also seen that PIGD with cleavage stage biopsy results lower birth rate for women of advanced maternal age .
PIGD has the potential to detect genetic issues not related to medical necessity like intelligence and beauty , so it opens the chance of using this technique to prepare designer babies , which is ethically not correct.
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