Cytogenetics and Cancer Research

I think I never mention about the relationship between cytogenetics and cancer research in this blog. Cytogenetic studies are proven that can assist to define the diagnosis and deliver clear prognostic differences in cancer. There are many cytogenetic studies of malignancy have been gone through and most of them are related to hematologic disorders. However, those studies constitute only small percentage of all cancer malignancies.
 

Clinical Value of Cytogenetic Studies in Malignancy Cancer

Recently, there has been a significant progress in knowledge of the recurrent abnormalities in many of solid tumors as well as hematologic malignancies. Consequently, the clinical value of cytogenetic studies in cancer malignancy has been appreciated after the cytogenetic studies of some solid tumors moving out of cancer research environment.
 
Apart from this, there would be little clinical value in doing cytogenetic studies in cancer malignancy if all the patients with a particular cancer died. The researchers only manage to probe the origins of cancer for those patients. However, after researching in all tumors type by using cytogenetic technique, the presence or absence of many of the genetic abnormalities found has been related to different responses to treatment. Since that, the genetic and cytogenetic studies start to be recognized as important and one of the best choices of treatment for a cancer patient.
 

Cytogenetic Studies Helps Diagnostic Investigation in Malignancy Cancer

Consequently, cytogenetic analysis of cancer malignancy is considered to provide rapid, accurate and specific results to aid the clinical professionals. This can help to choose the most appropriate type of treatment to the cancer patient in shorter time. However, John Swansbury stated that the diagnosis of a malignancy can be traumatic, and an accurate and early indication of every patient’s prognosis is valuable.
 
In conclusion, a cytogenetic study remains an essential part of diagnostic investigations of every patient with hematologic malignancy and certain solid tumors without denying the valuable contributions made by other genetic assays.

Reference: Methods in Molecular Biology, vol. 220: Cancer Cytogenetics: Methods and Protocols. Edited by: John Swansbury © Humana Press Inc., Totowa, NJ
 

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Down Syndrome is a popular topic in my Cytogenetics and Cancer Research blog now. I decide to write another post about the Down Syndrome to grab the attention from my readers. As I mentioned in my last post, Down Syndrome is caused by the non-disjunction of the chromosome during the meiosis. However, little is known about the causes for non-disjunction to occur as well as Down Syndrome in term of Cytogenetics. There are many hypotheses have been put forward to explain about the non-disjunction.
 

1. Enhanced Selective Miscarriage of Trisomy 21 Conceptions by Older Mothers

Analysis of the data shows that Trisomy 21 occurs in about 1 per 200 2000 of the births to mothers aged 18-24. The rate gradually increases in frequency to 1 per 300 births to mothers between 25 and 35. The rate continues to increase to 1 per 100 births to mothers at age 45 or older. Therefore, people start to come out with the hypothesis that is enhanced selective miscarriage of 21 trisomic conceptions by older mothers. This hypothesis claims that the increase of mother’s age is directly proportional to the enhanced selective miscarriage of trisomy 21. The non-disjunction seems to occur more frequently for older mother. During the meiosis, the older female’s gamete cell will miscarry two chromosome 21. Fertilization between this abnormal ovum with the sperm will cause the Down Syndrome.
 

 

2. Less Effectiveness for Oocyte Selection in Older Mothers

Another hypothesis is the decrease of effectiveness for oocyte selection in older mother. Oocyte selection is the process that determines which oocyte can enter the next stage of development. Only the normal oocyte will be selected and the abnormal oocyte will be eliminated. If the effectiveness of oocyte selection decrease because of the older age, the abnormal oocyte might be selected. This will cause the non-disjunction occur during the meiosis.
 

3. Sperm Aging Hypothesis

Some scientists raised up the sperm aging hypothesis claiming that the non-disjunction occurs because of the influence of sperm aging in male genital tract.
 

4. Chiasma Hormonal Hypothesis

Some scientists prove that there is an interaction between the hormonally governed rate of meiosis and the timing of chiasma terminalisation. The changing hormone levels during the menstrual cycle not only stimulate recommencement of meiosis in ovum, but also control the rate of meiosis through a limiting substance. The hormone levels and the length of the cycle will change with advancing age of the mother. Therefore the meiosis will slow down and chiasma frequencies decline. As we know, chiasmata is important for the meiotic chromosome bivalents to held together during meiosis. It will cause the premature separation during terminalisation. This can lead to Down Syndrome.
 

5. Consanguineous Parents Hypothesis

Some people said that the Down Syndrome is related to the consanguineous parents. Consanguineous parents are the parents who are blood-related.
 

In conclusion, there are many other hypotheses to explain about the causes of Down Syndrome. However, none of which was so far fully convincing. But what we need to aware of is the advancing age of woman. I will recommend you to have your child before 30 years old for woman to avoid from the risk of having Down Syndrome baby.
 

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