Whole Genome Sequencing (WGS)

What is Whole Genome Sequencing (WGS)?

Whole Genome Sequencing (WGS) is a DNA sequencing technique that refers to the identification of the entire genetic material—i.e., the complete genome—of an organism. This technique aims to determine the entire DNA sequence of an individual or organism.

Today, this technique has begun to be used in recent years in disease diagnosis and research to identify genetic variants. Most known disease-associated variants occur in “exons.” Therefore, Whole Exome Sequencing (WES) is an effective technique for identifying disease-causing variants. Furthermore, our experience in exome sequencing analysis allows us to better interpret and report the data.

However, for patients where exome sequencing fails to yield a diagnosis, for haplotype analyses used to determine drug sensitivities, for certain rearrangements not visible in exome sequencing, and for diagnosing diseases associated with repeat expansions, genome sequencing techniques have now become necessary.

The basic steps of WGS include:

1. Sample Collection:
   The first step is to collect a sample to obtain DNA from the individual or organism to be examined. This is usually done via a blood sample, tissue biopsy, or cell culture.

2. DNA Isolation:
   DNA is isolated from the obtained material. This is typically carried out using specific chemical and physical methods in the laboratory.

3. DNA Fragmentation:
   The isolated DNA is broken into smaller fragments. This fragmentation generally allows the production of DNA pieces of specific sizes.

4. DNA Sequencing:
   The fragmented DNA is sequenced, usually using high-throughput DNA sequencing machines. These machines read the nucleotides (adenine, thymine, guanine, and cytosine) of the DNA and determine the genetic code.

5. Data Analysis:
   The resulting DNA sequences are analyzed using computer algorithms. At this stage, the structure of the genome, genes, gene variations, and other genetic features are identified.

6. Interpretation of Results:
   The analysis results are interpreted by either computer software or expert geneticists. At this stage, it is possible to understand the individual's genetic risks, predispositions to genetic diseases, and other genetic traits.

WGS is a powerful tool for understanding an individual's genetic profile in great detail. This technique can be used for diagnosing genetic diseases, determining carrier status, discovering genetic variants, and in the field of personalized medicine. However, this comprehensive genetic analysis generates a large volume of data, and managing this data requires careful attention to ethical, privacy, and personal data protection concerns.

For Which Diseases/Conditions Is Whole Genome Sequencing (WGS) Used in Diagnosis or Detection?

Whole Genome Sequencing (WGS) is a technique that enables the identification of the entire genetic material and can be used in the diagnosis of many genetic diseases. Some of the diseases where WGS plays an important role in diagnosis include:

1. Monogenic Diseases:
   Monogenic diseases caused by a single genetic mutation can be identified using WGS. Examples include cystic fibrosis, Huntington’s disease, Duchenne muscular dystrophy, and conditions like hypothyroidism.

2. Cancer:
   The genomic analysis of cancer cells can be conducted using WGS. It can be used to identify the type of cancer, determine potential targets, and personalize treatment strategies.

3. Genetic Variants and Polymorphisms:
   WGS is effective in identifying genetic variants among individuals. It can be used to understand genetic polymorphisms, gene expression differences, and genetic risk factors.

4. Carrier Status:
   WGS is an important tool for identifying genetic diseases for which an individual may be a carrier. This information can be used for pre-marital genetic counseling and pregnancy planning.

5. Genetic Regions with Rearrangements:
   WGS can be effective in identifying large-scale changes in genetic structure. Structural variations, chromosomal changes, and translocations can be detected.

6. Metabolic Diseases:
   WGS can be used in the diagnosis of genetic metabolic diseases. For example, it can be effective in identifying the genetic causes of metabolic conditions such as phenylketonuria.

7. Rare Genetic Syndromes:
   WGS can aid in determining the genetic causes of rare genetic syndromes. These often involve complex and infrequently seen genetic conditions.

8. Pharmacogenetic Applications:
   WGS can be used to identify genetic factors that affect an individual's drug metabolism. This can play an important role in personalized medicine practices.

These diseases and conditions represent some of the many uses of WGS, but the list spans a wide range of areas. The potential of WGS is of great importance for a better understanding of genetically based diseases and the development of personalized medical approaches.