Medical Screening for Genetics Diseases!!!!!!(10 marks)!!!

There are several types of medical screenings commonly used in Hong Kong and they are :
(i)medical ultrasonography
http://www.ava.com.au/avj/0302/03020063.pdf
http://www.hku.hk/obsgyn/researchAct/interestPrenat.htm
See Early ultrasound detection of fetal structural abnormalities
http://www.ee.ic.ac.uk/eee2proj/gt2004/Files/TextFiles/Life%20Before%20Birth.pdf
http://www.answers.com/topic/obstetric-ultrasonography
http://www.ul.ie/~equines/Laboratory%208.htm

(ii)Chorionic villi sampling(CVS)
http://www.obgyn.upenn.edu/genetics/cvs.html
http://www.genzymegenetics.com/pdf/cvs_patient_brochure.pdf
http://www.healthatoz.com/healthatoz/Atoz/common/standard/transform.jsp?requestURI=/healthatoz/Atoz/dc/tp/tpcvs.jsp
http://www.wramc.amedd.army.mil/education/pat_edu/womenhlth/pregnancy/chorionicvillisamp.
http://www.answers.com/topic/chorionic-villus-samplinghtm

(iii)Amniocentesis
http://www.marchofdimes.com/professionals/681_1164.asp
http://www.medicinenet.com/amniocentesis/article.htm
http://patients.uptodate.com/topic.asp?file=pregnan/6937
http://www.obgyn.upenn.edu/genetics/Amnio.html
http://www.genecare.com/amnio.html
photo:http://www.nlm.nih.gov/medlineplus/ency/article/003921.htm

Addition knowledge: (Self-made)
(i)medical ultrasonography
How does this test carry out?
By using ultra-sound to test the growth of the internal organs digits and limbs of the foetus. As the above mentioned, their sex can also be known.

This technique can detect any abnormal internal organs (heart, liver and lung) growth as well as abnormal limb and digits growth. It can also help doctors to detect the foetus' sex too. It is safe for any mothers at any ages.

(ii)Chorionic villi sampling(CVS)
How does this step carry out?
A process to insect a needle into pregnant women's uterus via their abodmen under the help of ultrasonography by obstetrician so as to withdraw some chorionic villi from the uterus. Since the chorionic villi form zygote which will finally give foetus, these cells are idential.They are undergoing active cell division,mitosis too. By observing them under microscope, any abnormal genes can be found. Besides, the sex genes,XX and XY can also be observed. Hence, any diseases related to sex-linkage(haemophilia & colour blindness) can also be detected

This test is only for pregnant women whose ages are greater than 35. For this test, there are 2% of them to face the risk of miscarriage. However, according to the researches, the old the mothers, the greater is the chance for them to have Down's syndrome baby. The chance is greater than that of facing miscarriage. Hence it is worthy for them to carry out this test.
But for those younger mothers, this test is not recommended due to lower risk (2/1000) for them to have Down's syndrome baby. Comparing the chance of miscarriage with that of having a Down's syndrome baby in young-aged mothers, the chance for younger mother to have Down's syndrome baby is lower. Hence, this test is not recommended for them.

(iii)Amniocentesis
How does this test carry out
A needle is insert into pregnant women abodmen and then reach amniotic sac. The needle will withdraw 2ml amnotic fluid from this sac. The fluid being constantly sallowed by the foetus, must contain so living tissue such as chorionic villi when this fliuld come out of the foetus after sawllowing. The chorionic villi can be obtained by centrifuge 離心機.The abnormal or normal AFP value can be tested.

This test is good for pregnant women. And the chance of miscarriage is lower than than that of CVS. This test find out the level of alpha-feto protein (甲胎球蛋白)AFP. If this value of AFP is high, the foetus may have problem in their nerve systems.

I hope my writing can help you.

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