Molecular Genetic Method: Detection of Mutations
To confirm or exclude the carrier state of a specific mutation, a strict sequence of laboratory procedures is applied. This method allows for the high-precision differentiation of normal and altered regions of the genome.
Main stages of diagnostics:
- Amplification. The target gene region suspected of containing the mutation is multiplied repeatedly. Polymerase chain reaction (PCR) is used to obtain a sufficient amount of material for analysis.
- Fixation. The DNA samples obtained during PCR are applied and fixed onto special narrow strips of nitrocellulose.
- Hybridization. The fixed material is treated with specific probes—labeled oligonucleotides. These probes carry either a strictly normal or a mutant nucleotide sequence.
- Visualization. The results of hybridization are evaluated using autoradiography. This makes it possible to determine whether the patient's DNA has bound to the normal probe or the mutant probe, directly indicating the genetic status of the individual.
Basics of Gene Therapy
Gene therapy opens up possibilities for treating both hereditary pathologies and non-hereditary (e.g., infectious) diseases. The essence of the method lies in introducing therapeutic genes into the patient's cells, which are capable of either eliminating existing genetic defects or endowing the cell with entirely new functions.
Historical Precedent The starting point for the clinical application of this method was 1990. The patient was a four-year-old girl suffering from severe combined immunodeficiency caused by a mutation in the adenosine deaminase (ADA) gene. Treatment protocol (ex vivo):
- The patient's own lymphocytes were harvested.
- Under laboratory conditions (in vitro), a normal, functioning copy of the ADA gene was introduced into these cells using a retroviral DNA vector as a delivery vehicle.
- The modified lymphocytes with the corrected genetic apparatus were retransplanted back into the girl's body.
Today, the scope of gene therapy applications has expanded significantly. Methods are actively being developed and implemented to treat oncological diseases, hereditary syndromes, and severe viral pathologies, including HIV infection.
The Human Genome Project and the Nature of Hereditary Diseases
The foundation for the modern development of molecular medicine was the international Human Genome Project, launched in 1990. Its global goal was to precisely determine the nucleotide sequence in all human DNA molecules and to map (establish the localization of) all genes. To solve this large-scale task, cutting-edge second- and third-generation sequencing technologies are used.
Etiology and Perspectives According to statistics, out of approximately 10,000 known human diseases, about 3,000 are classified as hereditary. Their etiology is rooted in direct damage to the cellular hereditary apparatus. It is important to understand that such damage does not always imply the classic transmission of a defect from generation to generation. Complete sequencing of genes involved in the pathogenesis of various diseases is a major frontier in modern biochemistry and genetics. This will fundamentally transform approaches to early diagnosis and elevate patient treatment to a qualitatively new level.