Human body is made up of billions of cells. Cells may differ in size, structure and functions in different tissues but inside their nucleus contain similar 46 chromosomes, which consist of 22 pairs of identical autosomes, numbered from one to twenty two, depending on decreasing size, and one pairs of sex chromosomes, XX in females and XY in males. Half of chromosomes are derived from mother and other half from father. The chromosome are like double helix pearl string containing Deoxy Nucleic Acid (DNA). All the chromosomes are estimated to contain 3 billion of DNA molecules. Triplet of DNA carry the information of one protein. These portion of chromosome is called as ‘gene’. There are only 50 thousand to 1 lacks functional genes which encode for all the characteristics of the individuals.
New insight into the genetic basis of disease is being generated at even increasing pace. The explosion on information was ignited by advances in technology such as polymerase chain reaction (PCR) and automated DNA sequencing and fueled by rapid progress of Human Genome Project. Although its promises are immense, the inclusion of genetic in everyday practice is rather challenging task. Till date mostly genetic has increased our understanding of cause of diseases. In near future we can expect greater use of genetic in diagnosis, prevention and treatment of the diseases.
Now it is becoming apparent that genetic back ground play some role in virtually every disease directly or indirectly, they can influence disease susceptibility, interaction of genetic back ground with environment, patients response to infections and other disease and drugs.
Chromosomal and genetic disorders occur in about 10 to 25 percent of all fetus in mother’s womb. Serious genetic disorders can cause fetal death and abortion. Those who survive may have birth defects and / or mental retardation of various severity. About one in 50 baby born have some congenital abnormality or they are mentally handicapped. If we include the adult onset diseases like high diseases, psychiatric disorders, cancers and other diseases, then the number will swill.
GENETIC SCREENING AND TESTING:
During pregnancy and in new born baby, genetic testing can be use to detect many serious genetic diseases, so that step can be taken to prevent, treat them. If disease is likely to cause serious handicap in baby, the parents should be advised accordingly so that they can take decision to continue the pregnancy or not. These tests can be done either on mother’s blood like for Down’s syndrome (Trisomy 21), fetal blood like for phenyl ketonuria and familial hypercholesterolemia.
Ultrasonography is non invasive test and should be done to directly see the fetus at different stage of development to know physical abnormalities.
If parents have apparent genetic disorders, are known carrier of genetic disease then genetic testing can be carried out to diagnose the disease and possibility of transmission of disease to progeny.
At the time of birth all new born should be examined thoroughly to detect gross development and physical abnormalities, if found the other appropriate testing should be carried out.
With in 24 to 72 hours of birth blood sample of baby should be taken to detect some common diseases such as congenital hypothyroidism and many inherited metabolic disorders like phenyl ketounuria. If baby are suffering from hypothyroidism. Immediately, treatment by thyroxin hormone should be started so that they have normal physical and mental development. If suffering from phenyl ketonuria, phenyl alanine free diet can prevent the onset of neurological sequealae.
One suspicion, genetic testing of new born can be done to diagnose many other genetic disease, such as osteogenic imperfect muscular dystroply, etc.
In adults, on suspicion chromosomal, genetic, molecular testing can be under taken for diagnosis of various disorder these testing can be done in adult for diagnosis of existing established diseases of pre-symptomatic testing can by done know the risk of chronic pressure, such as high blood pressure, diabetes , cancer etc.
VARIOUD USES OF GENE THERAPY:
Whole organ transplant or tissue graft like of bone marrow, liver, kidney, heart, cornea, skin, bones, artery etc. have been used for years as way to replace the damaged organs and tissues. But it has limitation. Organ and tissue should be from the matched human being, risk of rejection exist and usually patients have to consume the drugs to prevent reactions and graft rejection for rest of life, which suppresses their resistance. The organs for transplant are not easily available. Idea of non human (non autologus) transplant can be made possible by modifying the genetic make up of animals and human replica organs can be produced in animals, which can be used for transplant. Even possibility of manufacturing of organ in genetic factory in unlimited number for organs are possible in near future. These organs / tissue will not have risk of reactions and rejection.
Gene therapy can be used in principle to modify all cells in the body including the germ cells. There cell line can produce ultra pure substances for use in treatment of various diseases in unlimited amount.
Germ line therapy would allow transmission of desired modified genetic information to next generation and desired number or great scientist, philosopher or criminal can be produced in desired number. But this is neither accepted not justified and legal.
In somatic gene therapy the differentiated cells of body can be modified and can be used to correct inherited diseases such as cystic fibrosis etc. and acquired genetic related diseases such as rheumatoid arthritis, cancers and many other diseases in near future.
By genetic engineering, human proteins can be manufactured in unlimited amount. The process is called as Recombinant DNA technology. Now this technique is widely used to manufacture human insulin, growth hormone, L.H, FSH. Erythropotein G-CSF, thrombopotein, interferon, interleukin, clothing factors VIII, IX, thrombolytic agents, antithrombolytic agents (Hiridin), etc. These substances are now widely for treatment of various diseases which were previously considered incurable.
The technique is also used to manufacture Hepatitis A and B vaccine, Rabies vaccine etc. and humanized monoclonal antibodies used for immune suppression or to treat specific types of cancer. New products, manufactured by recombinant DNA technique are appearing in market, which are being used for diagnosis, prevention and treatment of various diseases.
Gene therapy can be used to treat the genetic diseased which depends upon the nature of the disease. For inherited mono (single) gene disease such as Hemophilia, expression of missing clotting factor even in moderate amount is sufficient to cure the disease and patients will not require repeated blood transfusion.
Gene therapy is now considered or used for treatment of some cancer, providing chemo protection to normal cells so their chances of damage in minimized. It can be used for prevention of normal cells so their chances of damage in minimized. It can be used for prevention of repeated blockage of heart vessels thus preventing heart vessels thus preventing heat attack again, treatment of viral diseases like AIDS.
The gene can be thought of as a new way of diagnosis, prevention and treatment of many disease which are incurable at present. Hope that hurdles in gene therapy will be solved and safe effective gene therapy will be available easily and cheaply in near future.
Thanks,
Health, Oct-2012.
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