Improvements of Human Health

Health is the most important element in human life. An unhealthy people cannot enjoy most of the pleasure in life. The acquisition of a health life includes works in different areas. Basically, it can be divided into preventive aspect and theraputic aspect. For genetic diseases, the advancement of genetic study can give help in both areas.

Prevention of producing new patients

 Some works can prevent the birth of new patients. These works include :
(A)Genetic counselling,
Suggested Readings :
(1)Advanced-level Biology for Hong Kong , Book 2, by Y.K.Ho, Manhattan Press, pp.219-220
(2)Understanding Biology for Advanced Level, 4th Ed. by Glenn and Susan Toole, Stanley Thornes, pp.193-195
(3)Advanced Biology, Principles & applications, International Student Edition, by C.J.Clegg with D.G.Mackean, John Murray, pp.646


This includes the interview of a genetic counsellor. The genetic counsellor can analyst the genetic history of the families of the boys and girls and see whether their genetic histories indicate any risk of genetic diseases in their babies. This should be done before they get marry. If it indicates that there is a big conflict, or the risk of producing new babies with genetic diseases is very high, they can decide whether they would choose separation, or having no baby after marriage. Otherwise, they should be ready to take care of the defected baby for a long time, and sacrifing their life quality in the main part of their life and getting nothing when they become old.
The tool of analysis can be based on the pedigree analysis.

(B)Genetic screening,
Suggested Readings :
(1)Advanced-level Biology for Hong Kong , Book 2, by Y.K.Ho, Manhattan Press, pp.216-219
(2)Advanced Biology, Principles & applications, International Student Edition, by C.J.Clegg with D.G.Mackean, John Murray, pp.646


This includes the interview by a gynecological doctor. If the couple has a higher risk of carrying baby with genetic diseases, they need to make sure whether the baby she is carrying really has the genetic disease. If it is sure, the couple need to make prompt decision whether she would like to continue the carriage or termination of the pregnance (if it can be done morally and legally). Otherwise, they need to learn how to take care of the baby with genetic defects.
The tools of analysis includes the following works.

(a)Ultrasonic diagnosis,
Ultrasonic is a safe radiation by which we can observe the foetus in the uterus. This diagnosis is safe both to the mother and the foetus. But the image is not clear, so the result is rough. It can be used as a guide in conducting amniocentesis and collecting villus cell samples.
(b)amniocentesis,
This operation is potentially dangerous than the ultrasonic diagnosis. The gynoecologist will use a syringe to penetrate the abdominal wall and the wall of the uterus to collect some amniotic fluid from the uterus. By centrifugation, the foetal cells can be collected from the amniotic fluid. By the analysis of the DNA of the amniotic cells, it can be sure whether the baby has any genetic defect.
The penetration of the uterine wall is potentially dangerous. So, this operation may cause miscarriage at the rate of about 5%.
(c)Chorionic villus sampling,
In this method, a long tube is extended into the uterus to collect some cell samples of the chorionic villi. The defect of inheritance can be found through the karyotype analysis.
(d)foetoscopy,
A foetoscopy is a small camera at the end of a long tube. By the operation of the foetoscopy, the camera can enter into the deep of the uterus and take photo , video or make direct observation of the foetus.
(e)karyotype analysis,
Karyotype is the chromosome composition in the cell nucleus. If no structural or biochemical defect is detected in the foetus, karyotype analysis can be conducted. This can be done to the cell samples obtained from amniocentesis or chorionic villi. Then, the abnormality of chromosomes can be found.



Therapy of genetic diseases

 Suggested Readings :
(1)Advanced-level Biology for Hong Kong , Book 2, by Y.K.Ho, Manhattan Press, pp. 220-224
(2)Understanding Biology for Advanced Level, 4th Ed. by Glenn and Susan Toole, Stanley Thornes, pp. 124-125
(3)Advanced Biology, Principles & applications, International Student Edition, by C.J.Clegg with D.G.Mackean, John Murray, pp. 645


It is found that all genetic diseases are caused by the inability of functioning. This may be due to the lack of a substance or malfunctioning of a substance. No case of genetic disease owning to the presence of an extra material. So, the strategy in the therapy of genetic disease is about how to enable the patient to produce the correct material. This can be done by inserting the correcting gene. But anyway, no removal of gene is involved. This makes the gene therapy easier.

Scheme of work,
If we can prepare the correct gene / chromosome, we can put in into a vector, and infect the patient with the vector. Then, the vector can enter the body of the patient. When the vector reaches the target cells, the vector can combine with the receptor protein on the target cell. Eventually, the gene can enter the target cell. Once it enters the target cell, the gene will automatically enter the nucleus and combine with the host DNA to form a triplet structure. Then, the correct gene can exert its function.

In the past, no genetic disease can be cured. Now, by the advancement of genetics, it is believed that genetic diseases can be cured or remedied by gene therapy.

Gene therapy can be divided into two groups according to the target of the work.

(1)Somatic cell gene therapy,
This is the short-term, on-the-site therapy. It can help the patient to recover his/her body function, but this change cannot be transferred to the next generation. For example, we can transfer the correct gene for the production of insulin into the body of a diabetes patient. So, the gene can enter the beta cells of the Islet of Langerhands in the pancreas and form a triplet in the segment of the original DNA. Then, the added gene can be activated and start the transcription of normal insulin mRNA, and functional insulin can be produced.
(2)Germ cell gene therapy,
This is the long-term gene therapy. It is thought that if we can introduce the correct gene into the germ cells, and if the germ cell can have fertilization, then, all offspring producing would carry the normal insulin gene and would not have diabetes. To have germ cell gene therapy is not so easy as the somatic cell gene therapy. Because if the gene therapy is done to the sperms only, it would be too harsh. Sperms are produced so fast and also removed so fast. It is not easy to handle. If it is done to the sperm mother cells, how can the triplet survive over the meiosis is another problem. But any, this gives a hope to the patient.


Additional information can be obtained from the following websites :
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Reference 1(In English)


Human Genome Project

 Suggested Readings :
(1)Advanced-level Biology for Hong Kong , Book 2, by Y.K.Ho, Manhattan Press, pp.224-226
(2)Understanding Biology for Advanced Level, 4th Ed. by Glenn and Susan Toole, Stanley Thornes, pp. 129


Human genome project is the international project to find out the arrangement of genes along the humen DNA strands. The work is completed, but not yet understand. Biologist in different countries reveal the nitrogen bases sequences on the DNA strands. It is expected that we can know which segment represents which gene, or which segment can control which gene. If this is fully understand, we can manipulate human inheritance easily. So, if we find that a certain gene is defected, we can find out its location and the error, then, make change on it. The genetic disease is cured so easily. But there is still a long way to go, because of the limitation in knowledge. You can find the more detail information from the following websites :

Ref 1


Last Use Chinese Next

(13.02.2007)