Modern knowledge from the field of genetics has already entered the phase of its practical application in applied medicine. Today, scientists have developed a set of genetic screenings, or tests, that can identify genes that are the root cause of not only hereditary diseases, but also certain conditions of the body.
Trouble insurance
The child inherits from parents not only the color of the eyes and the shape of the nose, but also health. In many countries, genetic analysis (screening, from English screening - “sifting”) is already included in compulsory health insurance. In our country, this area of early diagnosis of child health is still only developing.
Each person carries in his genome up to ten defective genes, and in all we know more than 5 thousand diseases and pathological conditions associated with our gene set. This is statistics. Complex medical genetic screenings can identify up to 274 gene pathologies. That is why everyone who cares about the health of their unborn children should think about undergoing a genetic examination.
Not only for risk groups
Genetic screening is often offered to pregnant women. But not only for them, the results of genetic analysis can be useful. Genetic screening allows you to determine a person’s predisposition to a variety of diseases, gives information about the drugs that are most effective for a given patient. Studies provide information on a person’s personality, a tendency to be overweight, allow you to develop special diets and adjust your lifestyle.
Examinations of pregnant women (perinatal screening before birth) are used to determine the pathology of the fetus as part of its general diagnosis. In our country, mandatory genetic screening of newborns is carried out, but we will talk about this separately. Genetic analyzes of future parents are used to identify the degree of risk of a child with congenital gene pathologies.
We cannot but mention the genetic screening for establishing paternity and the degree of kinship, as well as the use of genetic data in the investigation of criminal offenses.
Nevertheless, there are risk groups
As it became clear, genetic tests can be carried out at the request of the patient and on the recommendation of a geneticist. Who is shown the following analysis:
- Spouses who have hereditary diseases.
- Married couples who are consanguineously related to each other.
- Women whose pregnancy is weighed down by an unfavorable history.
- People who are affected by adverse and mutagenic factors.
- Women over 35 years old and men over 40 years old. At this age, the risk of gene mutations increases.
Perinatal screening
This is a general concept for a number of examinations of pregnant women. It includes ultrasound, dopplerometry, biochemical analyzes and, in fact, screening of genetic diseases of the fetus, the purpose of which is to determine chromosomal abnormalities and malformations. Such studies include three main parameters in calculating the risks to the fetus: the age of the mother, the size of the collar space of the embryo, and the biochemical markers in the blood serum of the mother that belong to the fetus or are produced by the placenta.
All tests for pregnant women are divided into:
- Genetic screening of 1 trimester (up to 14 weeks of pregnancy). 80% of embryos with Down syndrome are detected.
- Screening 2 trimesters (from 14 to 18 weeks of pregnancy). Up to 90% of embryos with Down syndrome and other pathologies are detected.
Before, perinatal screening was recommended by doctors for women over 35 years of age, since it is they who have the risk of developing the Down syndrome in the fetus (chromosome pathology in the form of 3 chromosomes of 21 pairs). Today, the doctor offers such an examination to all pregnant women at their discretion.
The first trimester is the most important
To everyone who does not remember, we recall that in the first two weeks of its life, the embryo passes through the main stages of embryonic development, when the neural tube and the rudiments of all organs and systems of the body are laid, it is implanted in the uterus.
That is why pregnant women who suffered from acute respiratory viral diseases, herpes, hepatitis in the first trimester, were infected with HIV, had an X-ray (even with a dentist) or fluorography, used alcohol, smoked, took drugs or illegal drugs, sunbathed, pierced and even dyed hair, should think about consulting a geneticist.
What you can hear at the consultation
First of all, it is necessary to prepare for it. Future parents should know about hereditary diseases from their relatives, take medical records and the results of all examinations. The geneticist will study all the materials presented and, if necessary, send them for additional examinations (blood biochemistry, study of karyotypes).
It is important to remember that genetic screening is not 100% accurate. Sometimes, to clarify the pathology of the fetus, it is necessary to perform amniocentesis (amniotic fluid sampling), a chorionic biopsy, and other rather complicated tests.
What screening results look like
The correct result is expressed in the proportion of the chances of the fetus to be affected by Down syndrome, malformation of the neural tube and other pathologies. For example, 1: 200 means that the chance for a child to have a pathology is one in 200 cases. That is why 1: 345 is better than 1: 200. But that's not all. The doctor must definitely compare the indicators of your result with the indicator of the age category of the area where the examination takes place. In conclusion, we will talk about the high, medium or low risk of developing a defect.
But that is not all. An analysis requires an individual approach, which takes into account the indications of ultrasound, family history, indicators of biochemical markers.
Neonatal screening
This is the first genetic screening of a newborn. It was first introduced in 1962 for the early diagnosis of phenylketonuria in infants. Since then, endocrinological and metabolic disorders, blood pathologies and genetic abnormalities have been added to this disease.
The procedure for this screening is simple - a baby takes blood from the heel immediately after birth and is sent to the laboratory to check for diseases that are almost not diagnosed before the onset of symptoms, but when symptoms occur, lead to irreversible changes in the body. In case of a positive result, additional examination will be required.
What can reveal in the baby
This diagnosis is free and reveals the following diseases:
- Phenylketonuria is a systemic violation of protein metabolism, which in the later stages leads to mental retardation. The disease detected and balanced by a special diet in time does not develop.
- Hypotheriosis - decreased thyroid function. An insidious disease that leads to mental retardation and developmental delay.
- Cystic fibrosis is a serious disease associated with a gene mutation. In this case, the work of many organs is disrupted. There is no treatment, but diet and special enzymatic preparations stabilize the patient's condition.
- Adrenogenital syndrome - adrenal cortex function is impaired, which leads to dwarfism.
- Galactosemia is a deficiency of enzymes responsible for the exchange of galactose.
However, five diseases are clearly not enough. For example, in Germany, newborn screening includes 14 diseases, and in the USA - 60.
Genetic tests can save a life
Premarital screening of spouses to identify the carrier of mutant genes will enable doctors to more closely monitor the course of pregnancy, perinatal diagnosis will reveal pathologies, and all this will help ensure early correction of hereditary diseases in the child.
Natal diagnosis of newborns will reveal diseases that, with timely correction, will enable the child to develop normally. Early diagnosis of monogenic diseases (hemophilia or congenital deafness) will allow you to avoid many errors, sometimes fatal.
Genetic screenings in adults reveal multifactorial diseases - cancer, diabetes, Alzheimer's disease. Identification of the genetic tendency to these pathologies determines a complex of preventive measures aimed at reducing the risks of their development. Already today there are cases when the causes of blood cancer were identified at the genetic level, and the disease was able to be transferred to the remission stage due to gene studies.
And they can help improve it.
A promising direction is the development of genetic Lifestyle-tests. They are designed to track the tendency of the body to various environmental factors. They will show a predisposition to assimilation of various nutrients and their metabolic rate. And an experienced nutritionist will tell you how to eat and how to exercise based on your genetic characteristics.