Genetic testing is a medical test that involves the analysis of blood samples or other body tissues. It helps to identify the changes that has happened to the genes, chromosomes and proteins and thus helps to determine whether a mother or father or their baby is carrying a genes for any inherited disorders.
Genes are the subunits of DNA and DNA exist as two long spiral double helix strands in each and every cell of the body and produce proteins that are vital for the functioning of the cell as per the genetic information provided by the genes. Each DNA consists of two pairs of chromosomes that carry genes, one pair inherited from the father and one pair from the mother.
Genes have different variants called alleles and a dominant allele prevails over a normal or recessive allele. A person who inherits disease causing recessive gene does not suffer from the disease rather he act as a carrier and have about 50-50 chance to transmit that disease to his offspring. If both parents have disease causing recessive gene that one among their four children is at the risk of developing this disease.
Genetic testing helps to detect the defective genes and also identifies whether an embryo is carrying those defective genes and is prone to develop any hereditary disease. For conducting a genetic test only a tint of blood sample, bone, skin, hair or any other tissue is required.
Why Doctors Suggest Genetic Testing
Genetic testing is used by doctors to know whether the parents who have a family history of any inherited disease carry any altered gene and also to find out how much is the chances for passing on that disorder to their children. If only any one of the parent is having an altered gene and the other is normal then their children may not get that disorder instead these kids may act as carries of this particular disorder and may pass the disease causing gene to their offspring.
Partners having a child with birth defects are also recommended to carry out a genetic test. It is not necessary that the birth defects are always due to altered genes but it can also be due to exposure to certain radiation, toxins, physical trauma before birth or infection. It may also be due to the spontaneous error that happened within the child’s gene and not due to the defective parental gene. In such situations doctors screen embryos and find out the possible genetic disorders in them.
Women who had two or three miscarriages are also recommended to carry out genetic test as at times chromosomal problems of the fetus may be the reason for miscarriages and in many instances miscarriages pin point certain genetic disorders. Women who had delivered a still baby with physical abnormalities are also recommended to undertake genetic test. This is because certain genetic disorders lead to physical abnormalities that provide a distinctive appearance to the child.
If a woman gets pregnant after 34 years then the chances for having a child with chromosomal abnormalities such as trisomy are more. Similarly older fathers also have a risk of getting a child with genetic mutations. Hence in such cases also doctors recommend genetic testing. Genetic testing at times also helps to confirm or rule out the diagnosis of having a genetic disease in an adult. The test results help the people to make family planning, life decision, career choice etc.
Genetic Testing During Pregnancy
In order to carry out a genetic test the pregnant women have to undergo either amniocentesis or chorionic villus sampling. For an amniocentesis doctors insert a hollow needle through the woman’s abdomen and take out a little amniotic fluid that surrounds the developing embryo. This test should be carried out between 16th to 18th weeks of pregnancy and this fluid is further tested to determine the genetic abnormalities.
At some instances amniocentesis may induce a miscarriage. To accomplish a chorionic villus sampling doctors take a small piece of placenta from the woman’s womb and then check it for genetic problems. This test should be carried out at 10th to 12th weeks of pregnancy but this test carries the risk of miscarriage. Hence such tests should be carried out only with the consent of the patient.
Pros and Cons of Genetic Testing
Genetic test helps to diagnose and treat certain conditions and it also allows the families to avoid kids with genetic abnormalities. It also helps to identify the risk of having dreadful diseases such as cancer and treat them at appropriate time to save the life. But the major defect of this test is that it can only provide the probability or susceptibility of having the disease and it is not necessary that a baby carrying mutated gene develop that disease.
The final assumption depends mostly on the ability of the physician to interpret the results. More over many of these mutations in association with environmental and other factors cause the disease. Hence while interpreting a result there should be a false positive and false negative interpretation to rule out the chances of genetic problems. There are also chances that a laboratory test may have errors due to contamination of chemicals used for testing, sample misidentification etc.
Since genetic testing can affect the lives of the people it should be handled with utmost care. The test report at times questions the privacy of the people. This is because once a baby is found to a carrier of genetic disorder or likely to develop that disorder then it may affect his future insurability or employability. Hence before doing a genetic test doctors should inform their patients about the benefits, risks, efficiency and significance of genetic testing.
Above all the results of the genetic test are kept highly confidential and are given only to the authorized receiver and also the future access to a genetic test result should be limited. Certain genetic tests are highly essential to support or encourage the development of a fetus or a newborn baby. Above all the knowledge of having a child that carries a high risk gene helps parents to modify or plan their kid’s lifestyle and reduce or control the chances of developing the disease.
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