Scientific approach
Objectively speaking, no parent is insured against this risk. Each of us carries an average of 10-12 defective genes, which we received from our relatives and, probably, we will give to our own children. Today, science knows about 5000 hereditary diseases, which develop due to problems in the genetic apparatus of man - in genes or chromosomes.
They are divided into three main groups: monogenic, polygenic and chromosomal.
Today almost any pathology can be explained from the point of view of genetics. Chronic tonsillitis - hereditary defect of immunity, cholelithiasis - hereditary metabolic disorder.
Types of diseases
Monogenic diseases are caused by a defect of one gene. For today, about 1400 such diseases are known. Although their prevalence is low (5-10% of the total number of hereditary diseases), they do not completely disappear. Among the most common in Russia - cystic fibrosis, phenylketonuria, adrenogenital syndrome, g-lactosemia. To identify these pathologies, all newborns in our country undergo special tests (unfortunately, no country in the world can check the kids for the presence of all defective genes). If a deviation is detected, the baby is transferred to a special diet, which must be observed before the age of 12, and sometimes up to 18 years. If the sick parents are born healthy children, then all the offspring of the latter will be "without a defect".
Polygen (or multifactorial) diseases are associated with a violation of the interaction of several genes, as well as environmental factors. This is the most numerous group - it includes about 90% of all human hereditary diseases of their prevention and subsequent treatment.
Transmission paths
The main transmitter of the disease is a sick mother or father. If both suffer from the disease, the risk increases several times. However, even if you and your spouse are healthy, there are a number of defective genes in your body. They are simply suppressed by the normal and "silent." In the event that you have the same "silent" gene with your husband, your children may develop a hereditary disease.
Its inheritance feature is in diseases "linked to the sex" - hemophilia, Günter's disease. They are controlled by genes that are in the sex chromosome. Parents of the patient have some types of oncology, developmental anomalies (including hare lip and wolf mouth). In some cases, parents transmit not the disease itself, but a predisposition to it (diabetes mellitus, coronary heart disease, alcoholism). Children receive an unfavorable combination of genes, which under certain conditions (stress, serious trauma, poor ecology) can lead to the development of the disease. And the more pronounced the disease in mom or dad, the higher the risk.
Chromosomal hereditary diseases of man, their prevention and treatment are given a huge amount of time and effort, they arise because of the change in the number and structure of chromosomes. For example, the most famous anomaly - Down's disease - is a consequence of the tripling of the 2 chromosomes. Such mutations are not so rare, they occur in 6 of the newborns. Other common diseases are the syndromes of Turner, Edwards, Patau. All of them are characterized by multiple vices: a delay in physical development, mental retardation, cardiovascular, genitourinary, nervous and other malformations. Treatment of chromosomal abnormalities has not yet been found.
the child can be healthy, but if the mother is a carrier of a mutant gene, the probability of producing a sick boy is 5%. Girls are born healthy, but half of them, in turn, become carriers of the defective gene. The sick father does not transmit the disease to his sons. Daughters can get sick only if the mother is a bearer.
From the Egyptian Tomb
Pharaoh Akhenaten and the queen Nefertiti the ancients depicted with a rather unusual appearance. It turns out, it's not just the artistic vision of the painters. According to the unnaturally elongated, "tower" form of the skull, small eyes, abnormally long limbs (the so-called "spider fingers"), undeveloped chin ("bird face"), the scientists identified Minkowski-Shafar syndrome - one of the hereditary anemia (anemia).
From Russian History
Violation of blood clotting (hemophilia) in the son of the last Russian Tsar Nicholas II Tsarevich Alexei is also hereditary in nature. This disease is transmitted through the maternal line, but is manifested exclusively in boys. Most likely, the first owner of the hemophilia gene was Queen Victoria of Great Britain, Alexei's great-grandmother.
Difficulties in identifying
Hereditary diseases do not always manifest themselves from birth. Some types of mental retardation become noticeable only when the child begins to speak or go to school. But the gutting of Goettington (a kind of progressive mental retardation) can generally be recognized only after years.
In addition, the "silent" genes can become pitfalls. Their action can appear throughout life - under the influence of negative external factors (unhealthy lifestyle, taking a number of drugs, radiation, environmental pollution). If your baby falls into a risk group, you can undergo a molecular genetic examination that will help to identify the probability of the disease in each case. Further, a specialist can prescribe preventive measures. If the sick genes are dominant, it is impossible to avoid the disease. You can only relieve the symptoms of the disease. Better yet, try to warn them before delivery.
Risk group
If you and your spouse have one of these factors, it is better to undergo medical genetic counseling before pregnancy.
1. Presence of several cases of hereditary diseases on both lines. Even if you are healthy, you can be carriers of defective genes.
2. Age is more than 35 years. Over the years, the number of mutations in the body is accumulating. The risk of a number of diseases is growing exponentially. So, with Down's disease for 16-year-old mothers, it is 1: 1640, for 30-year-olds - 1: 720, for 40-year-olds - already 1:70.
3. Birth of previous children with serious hereditary diseases.
4. Several incidents of miscarriage. Often, they cause serious genetic or chromosomal abnormalities in the fetus.
5. Prolonged intake of medicines by a woman (anticonvulsant, antithyroid, antitumor drugs, corticosteroids).
6. Contact with toxic and radioactive substances, as well as alcoholism and drug addiction. All this can cause genetic mutations.
Thanks to the development of medicine, now all parents have a choice - to continue the family history of a serious illness or to interrupt it.
Methods of prevention
If you are at risk, you need to go through a consultation with a geneticist. Based on a detailed pedigree and other data, he will decide whether your fears are justified. If the doctor confirms the risk, you should go through genetic testing. It will determine whether you are carrying dangerous flaws.
If the danger of producing a sick kid is too high, experts advise instead of natural conception to resort to in vitro fertilization (IVF) with preimplantation genetic diagnosis (PGD). PGD allows one cell taken from the embryo to understand whether it is healthy or ill. Then, only healthy embryos are selected and implanted into the uterus. After IVF, the pregnancy rate is 40% (more than one procedure may be required). It should be remembered that testing the embryo is carried out for a specific disease (which is identified in advance of increased risk). This does not mean that the child born in the end is guaranteed against other diseases, including hereditary diseases. PGD is a complicated and not expensive method, but it works well in skillful hands.
During pregnancy, it is necessary to visit all planned ultrasound and donate blood to the "triple test" (to assess the degree of risk of development of pathology). With the danger of chromosomal mutations, a chorionic biopsy can be performed. Although there is a threat of abortion, this manipulation makes it possible to determine the presence of chromosomal abnormalities. If they are found, the pregnancy is advised to be interrupted.