WES whole-exome sequencing (prenatal diagnosis)

Whole-genome sequencing is a method that allows you to study mutations in human genes.

The goal of a complete exome sequencing (exome is the “coding” part of the genome) is to try to find the genetic cause of the signs and symptoms you or your child have.

In prenatal diagnostics, this means that we can analyze the genetic information of the unborn child before birth. It helps to identify possible genetic abnormalities or diseases before birth, so that parents and medical staff can plan possible prevention and treatment for the child in advance.

Whole-genome sequencing is one of the most comprehensive and reliable genetic tests for detecting disease-causing changes, as it analyzes approximately 20,000 human genes. This is done with the help of modern next-generation sequencing technologies. Despite the fact that the exome covers only about 1% of the genome, 85% of all disease-related mutations are located there.

Whole-genome sequencing is most suitable for such patients:

• Patients who are faced with a complex nonspecific genetic disease that does not have an exact diagnosis.
• Patients who are suspected of having a genetic disease for which there is no specific genetic test available.
• Those who have already had previous genetic testing, but it was unsuccessful.

Whole-exome WES sequencing can help identify a variety of genetic diseases and abnormalities, including:

• Syndromes with developmental abnormalities associated with certain parts of chromosomes: Treacher Collins syndrome, Noonan syndrome.
• Monogenic diseases: these are genetic diseases caused by mutations in one specific gene: cystic fibrosis, phenylketonuria, muscular dystrophy, and others.
• Rare genetic diseases: These are diseases that result from a rare combination of genetic mutations: hemophilia, Duchenne muscular dystrophy.
• Hereditary forms of cancer: Some forms of cancer have a strong genetic component and can be detected by whole-exome sequencing: Breast cancer, Lynch syndrome, also known as familial colon cancer syndrome, is a genetic disorder that increases the risk of developing certain types of cancer, particularly colon cancer and endometrial (uterine) cancer in women.
• Other genetic disorders: Such as genetic disorders of the immune system (hereditary immunodeficiencies, autoimmune diseases), metabolic disorders (phenylketonuria, galactosemia, alkaptonuria), and others.

If a child has a genetic mutation, one of the parents may have the same genetic mutation.

For example, if a child is diagnosed with a BRCA1 mutation (which can cause breast, ovarian, and other cancers), one of the parents is likely to have the same mutation.

For example, if your doctor finds out that you have a genetic variant that is closely associated with heart disease, he or she may recommend a proactive treatment plan that focuses on healthy foods that will be beneficial to the cardiovascular system and certain habits and lifestyle choices. A newborn or a child with a genetic birth defect can receive specialized treatment at an early stage of life.

How the testing takes place:

The material for the analysis is amniotic fluid (10 ml, collected after 17 weeks of pregnancy) and maternal blood from a vein with EDTA-K (4 ml test tube).

The turnaround time is about 30 days.

Whole-genome sequencing is one of the most extensive genetic tests available because it looks at more genes than most genetic tests, and it can identify the genetic cause of signs and symptoms even if previous genetic testing has not.

Technical characteristics:

• Whole exome sequencing is performed using the Twist Exome 2.0 kit.
• The coverage depth for all Exome sequencing is 100x.
• The created library is sequenced either on the Illumina NovaSeq platform
• 6000 NGS, or on the MGI DNBSEQ-G400 platform.
• Raw data is provided in FASTQ format.