What are other Names for this Test? (Equivalent Terms)

• Whole-Genome and Exome Sequencing

What is DNA Sequencing? (Background Information)

• DNA Sequencing (Whole-Genome and Exome Sequencing) is a specialized genetic testing technique that is used to detect chromosomal abnormalities that are too tiny to be detected using conventional microscopic studies
• DNA Sequencing can detect very minuscule alterations in chromosomes, such as a change in a single base. Sequencing reads the exact order of bases (As, Cs, Gs, and Ts) along a piece of DNA
• The DNA in the cells is double-stranded. Each strand contains a mixture of four bases, namely A, T, C, and G. The bases of each strand bind with each other to hold the DNA together. The DNA is only able to bind if the bases on the two strands are complementary to each other
• An individual’s sequencing results can be compared to standards of what is commonly seen in the population. Interpreting the sequence data is very complex and still has a long way to go before the full diagnostic potential is reached. However, DNA Sequencing is known to provide the most comprehensive analysis of genes and chromosomes to date
• There are different types of DNA Sequencing that include:
  • Whole-genome sequencing (WGS)
  • Whole exome sequencing (WES)
  • Gene panel sequencing
  • Single gene sequencing

Note: Molecular testing has limitations due to the molecular method and genetic mutational abnormalities being tested. This can affect the results on a case-by-case basis. Consultation with your healthcare provider will help in determining the right test and right molecular method, based on individual circumstances.

What are the Clinical Indications for performing the DNA Sequencing?

Following are the clinical indicators for performing the DNA Sequencing test: 

• DNA Sequencing is most commonly used to identify serious undiagnosed disorders where a small genetic change is most likely the cause
• To assist (and in some cases, confirm) the initial diagnosis
• If there is a family history of the medical disorder/condition
• To distinguish other conditions that have similar features (signs and symptoms)
• To help in determining treatment options

How is the Specimen Collected for the DNA Sequencing?

Following specimens may be collected for DNA Sequencing test:

• Blood
• Saliva
• Cheek swab cells

The specimen sample requirements may vary from lab to lab. Hence, it is important to contact the testing lab for exact specimen requirements, before initiating the testing process.

• Process of obtaining the sample: As outlined by the laboratory testing facility
• Preparation required: As outlined by the laboratory testing facility

Cost of DNA Sequencing:

• The cost of the test procedure depends on a variety of factors, such as the type of your health insurance, annual deductibles, co-pay requirements, out-of-network and in-network of your healthcare providers and healthcare facilities
• In many cases, an estimate may be provided before the test is conducted. The final amount may depend upon the findings during the test procedure and post-operative care that is necessary (if any)

What is the Significance of the DNA Sequencing Result?

The results of the DNA Sequencing may indicate if any of the following chromosomal anomaly has taken place:

• Deletion/microdeletion
• Duplication/microduplication
• Number and types of genes involved (such as deleted/duplicated)

Advantages of DNA Sequencing: 

• Sequencing is known to provide the most comprehensive analysis of genes and chromosomes to date
• Sequencing can also detect changes in genes and chromosomes when there may be no obvious genetic explanations for an individual’s health or developmental concerns
• Additionally, for some genetic disorders, it may be beneficial for adult carriers to be aware of their diagnosis so they may monitor their health appropriately 

Limitations of DNA Sequencing: 

• Interpreting the results of genome and exome sequencing is quite complicated because every individual has a unique DNA sequence. These small genetic differences are known as variants. Sometimes these variations in the DNA can make interpreting test results very difficult
• It may take a long period of time for obtaining the results as the analysis and interpretation of data may involve several experts 

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

Many laboratories may not have the capability to perform this test. Only highly-specialized labs with advanced facilities and testing procedures may perform this test.

Please visit our Laboratory Procedures Center for more physician-approved health information:

http://www.dovemed.com/common-procedures/procedures-laboratory/