Genetic Testing

Introduction:

Genetic testing is the test conducted to check the genes for any alterations or mutation or any other changes that can lead to any illness or disease. Although this type of testing is beneficial in early diagnosis, treatment, and prevention of the disease, it also possesses certain limitations. A medical geneticist or a genetic counselor can help you with this process.

According to the definition, Genetic Screening is the testing of the population to identify individuals at risk for a genetic disease or for transmitting a gene for genetic disease. It helps in the detection of phenotype and genotype. It involves the analysis of chromosomes (DNA), protein, and certain metabolites in order to detect heritable disease-related to genotype, mutation, phenotype, or karyotype for clinical purposes.

What Is the Principle?

The principle involves the initial collection of DNA samples, the addition of restriction enzymes followed by a radioactive probe. Later, gel electrophoresis is done, and finally, the disease-causing or linked fragment is identified.

What Are the Procedures?

The main three procedures involve genetic screening followed by genetic counseling, and finally gene therapy. Hence, genetic screening is a part of the procedure and is done first.

How Is Genome Sequencing Different From Genetic Testing?

Genomic sequencing can be done in cases when the diagnosis could not be clearly made from genetic testing, but a genetic cause is suspected. Genome sequencing is a process that analyzes a sample of DNA taken from blood.

Is Genetic Testing Really Required?

Genetic testing is important to determine the risk of developing certain diseases and screening and sometimes medical treatment of the same. Different types of genetic testing are available for various reasons as follows:

• Diagnostic testing can be done in cases of symptomatic patients who may have a certain genetic disease.

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• Presymptomatic and predictive testing. If there is a family history of a genetic condition, this testing can help in assessing whether you are at risk of developing the condition.

• Carrier testing. This is to check whether you can be a carrier of the mutated or altered gene that may cause the disease.

• Pharmacogenetics. This will help in assessing the efficacy of the medicine in treating a condition if it shows any association with a genetic cause.

• Prenatal testing. This testing is done in an expecting mother. There are various tests available like amniocentesis, maternal blood analysis, chorionic villi sampling, fetal liver biopsy, polar body biopsy, blastocyst biopsy, etc.

• Newborn screening. This is the most commonly done genetic testing. The newborn is assessed for any genetic alteration or mutation. It can help in checking for sickle cell anemia, etc.

• Preimplantation testing. This test is very useful when in vitro fertilization is being attempted.

• Characterization of tumor types. In this, the tumor or cancer association with genes can be seen.

• Inherited predisposition. It can be useful in genes being transmitted via hereditary, like breast and ovarian cancers, Alzheimer's disease.

• Also, it is useful in adult-onset disorders in which presymptomatic testing can be done, like in Huntington's disease.

• Research genetic test. Research is a very big field recently to get answers to many questions. Hence, this type of genetic testing can help in finding the association between diseases and genes, various treatment modalities, etc.

Are There Any Risks Associated?

A little risk can be associated. There is almost no risk associated with blood and cheek swab tests. Although, prenatal testing like amniocentesis or chorionic villus sampling can sometimes cause miscarriage.

Genetic testing can also have emotional, social, and financial risks. Hence, discussing with your physician is important before going ahead with the testing.

How Can You Prepare for This?

Before going ahead with this testing, gather all details about the disease history or any known genetic disease that runs in the family and the pattern. Later, consult your physician to get it checked.

What Is to Be Expected?

A sample of blood, skin, amniotic fluid, or other tissue will be collected depending on the type of test involved, and then it will be sent to a laboratory for analysis of the sample.

What Type of Results Can Be Obtained?

There can be either a positive or negative result. Sometimes, it can be inconclusive.

If it comes positive, it indicates there is an association with a genetic disease, and the time taken for the result to come depends on the type and purpose of the test. Once there is a positive confirmation, talk to your physician to decide on the diagnosis and treatment plan. In addition to this, it is possible for you to participate in research studies.

A negative result indicates that a mutated gene was not detected by the test but cannot be 100 percent guaranteed that there is no disorder.

If the results are inconclusive, further genome screening can be done.

What Is Genetic Counseling?

It is defined as a communication process in which individuals seeking advice are given all scientific information so that they can make a decision about current or future pregnancies. It can be broadly divided into two types of visualization of the fetus and analysis of the fetal tissue. The fetus can be visualized using ultrasonography, radiography, or fetoscopy.

This type of counseling will give a clear picture to the expecting parents or those planning to conceive of taking a decision regarding pregnancies and various prevention and treatments in case of established or risk of genetic disease.

How Will the Disease Be Identified?

Initially, a family pedigree chart will be made using information given by the mother. This pedigree chart is made for three generations. The chart is analyzed, and the mode of inheritance of the genetic condition is determined. Then the risk of recurrence of the condition is calculated as high or low, followed by decision making or diagnosis.

Genetic testing is a useful tool in assessing genes so that any gene-related disorder can be diagnosed early and managed. For more details on the same at the earliest, you can consult your physician or a specialist via online medical platforms.