More recently, computer and positron emission tomography and other methods of sensitive diagnostics using instrumental analysis have become common clinical practice. One of such promising methods for the early diagnosis of various pathologies is a method based on the study and analysis of genetic markers. Modern laboratories have long been offering services for the determination of tumor markers and markers of various pathological conditions in human blood. What are genetic blood markers, how are their indications used, what are they - we will talk about this in this article.
Let's define concepts
A genetic marker is a label, the nucleotide sequence of a DNA (deoxyribonucleic acid) region with a known position on a particular chromosome. This is a convenient trait for analysis that allows you to track the nature of the inheritance of traits linked to this marker.
Modern molecular biology distinguishes the following types of molecular genetic markers:
- Plots of structural (encoding specific proteins) genes.
- Non-protein coding regions of structural genes.
- Markers of various DNA sequences that are not related to structural genes.
- Microsatellite DNA regions (short repeats).
Genetics in our life
Since 2003, when the human genome was sequenced (The Human Genome Project, HGP), genetics has ceased to be a fundamental science, and has entered the field of its practical application. DNA marker research is used today in many branches of medicine and not only.
Genetic analysis is used to identify pathologies in a patient, to study a specific allergic reaction, when assessing the risks of developing hereditary pathologies in adults and children (asthma, diabetes, thrombophilia, schizophrenia, epilepsy).
In prenatal (before birth) medicine, it is genetic analysis that allows to identify pathologies in the embryo (Down, Klinefelter, Edwards, Turner syndromes). Genetic markers can determine the causes of infertility and abortion.
Gene diagnostics are widely used in pharmaceuticals. It gives an explanation for the fact that drugs do not affect people in different ways. And why the side effect of drugs has a more severe effect on a certain category of people.
Well, in addition, genetic analysis today allows you to determine in which sport your child can achieve the best results, and which diet is right for you.
Molecular genetic diagnostics
This rather young diagnostic method for examining a person’s personal “code” makes it possible to detect viral and bacterial infections and pathological mutations in genes. Identification of genetic markers in the genome allows you to fairly accurately assess the risk of hereditary and not only diseases.
The main advantage of such a diagnosis is minimal medical intervention, because every cell in our body (including blood cells) contains a complete set of all our genes. It is blood from a vein that is the most common material for this study, although other biological fluids (saliva, amniotic fluid, secretions) or tissues (scrapings of mucous membranes, hair, nails) can be used.
How it's done
In Russia, not all clinics have the opportunity to offer molecular diagnostics, although this non-invasive method of examination with high accuracy of results is already widespread in countries with a developed healthcare system.
The stages of the study are as follows:
- The intake of biomaterial from the patient.
- Isolation of DNA or RNA.
- A study on one of the methods of molecular analysis.
- Studying and interpreting the result.
- Conclusion of a geneticist.
Modern technologies
The identification of polymorphism (diversity) in the structure of DNA has in its arsenal many methods, the main of which are as follows:
- Molecular cytogenetics method - analyzes DNA-based markers or RFLP markers (restriction fragment length polymorphism, RFLP). The method uses the extraction of DNA, obtaining its fragment and its analysis using a DNA spectrum specific for each individual.
- PCR markers. The method uses a polymerase chain reaction (PCR) using specific DNA primers (sections) with different lengths and nucleotide sequences. The most popular method in molecular diagnostics.
- Fluorescence DNA Hybridization Method (FISH). This method works with atypical sections of DNA localized in a particular locus of the chromosome. It is this method that is used to identify oncological pathologies (tumor markers), in prenatal diagnosis (markers of hereditary diseases of the fetus).
- Microchipping method. In this case, the fluorescence-marked sections of the patient’s DNA are compared with samples on microarrays. It is widely used in cardiology (genetic markers of thrombogenic risk) and in oncology.
When it matters to the patient
There are situations when the appeal to genetic analysis becomes vital, namely:
- When an accurate diagnosis is needed. For example, when determining allergens, viral infections.
- When prevention can prevent the development of pathology. For example, with a positive analysis for genetic markers of thrombophilia (a tendency to form blood clots in the bloodstream), lifestyle adjustments are possible to prevent pathology.
- When the life of the patient depends on the effectiveness of the treatment. This is exactly what happens when evaluating the effect of therapy on the course of cancer.
When is it important for the future?
An important area of genetic analysis is risk assessment when planning or having a baby. So future parents can study genetic compatibility and assess the risks of hereditary pathologies in posterity. Using the methods of molecular genetic diagnostics, one can study the condition of the fetus during pregnancy, identify dangerous syndromes and developmental pathologies.
In a born baby, you can diagnose diseases and assess the risks of their development. For example, in the presence of genetic markers of diabetes mellitus identified in a child, it is quite possible to adjust nutrition to prevent the development of non-hereditary forms of diabetes.
In addition, these methods with a high degree of probability are used in determining paternity and motherhood.
Cancer markers in the fight against cancer
The realism of modern society with its polluted environment and the presence of bad habits gives a rather disappointing prognosis regarding oncological pathologies. And the main problem of high mortality among cancer patients is the identification of the disease in the late stages of its development.
It is the genetic markers that are characteristic in the presence of the oncological process that can identify pathology in the early stages, which significantly increases the survival rates of patients. Tumor markers are biological characteristics that affect the clinical course of the cancer process and its prognosis. In addition, a blood test for genetic markers of oncopathology makes it possible to track the response of the patient to the therapeutic effect.
Genetics guard the law
DNA does not lie. It is on this that the work of modern forensic geneticists is built. A comparative analysis of DNA markers from crime scenes with a database is today one of the priority areas in the investigation of serious crimes.
Forensic genetics uses 16 DNA markers and a gender marker. Recent advances in this area suggest the race, height, and even appearance of the offender.
However, despite the successes, mistakes are still encountered in judicial practice today. But no one is safe from them.