In addition to quantitative deviations in the human karyotype, anomalies of individual genes and DNA segments are possible. Even the most insignificant defect of even the shortest part can be fatal. However, sometimes a person may not suspect the existence of serious genetic pathologies during the whole life. So, it all depends on an individual case.
Both parents equally transmit genetic information to their child and can theoretically present their offspring all deviations from the normal karyotype accumulated in it by many generations of ancestors. However, the fear of getting any sore from grandmother or a great-grandfather is not always justified.
For example, the scourge of our time is cancer. To date, the hereditary nature of cancer has not been established. However, you can inherit a predisposition to it. Among the hereditary (family, such that occur with several relatives) diseases there is colon polyposis. It under unfavorable circumstances can transform into a malignant tumor. It is not at all necessary that you develop cancer if one of your relatives has it. However, do not forget that the tendency to it exists and bad habits, unhealthy diet and environmental pollution can wake up sleeping genes. Moreover, a healthy lifestyle does not hurt in any case. Or on the contrary, your relatives can be healthy, and you will be the first in the family who will have a fatal disease.
Another ailment is varicose of veins. "The gene of varicose veins" could not be found by the scientists who deciphered the human genome. That is, varicose disease is not inherited. However, weakness of the walls of the veins and valves can be transmitted from parents. If you are overweight, wearing tight pants and tight shoes, spending a lot of time on your feet, the risk of developing varicose veins for people with hereditary weakness of veins and valves will be several times higher than those whose relatives were not familiar with this vascular disease.
Diseases with a hereditary predisposition also include bronchial asthma, gastric and duodenal ulcers, alcoholism and drug addiction, psoriasis, eczema, atopic dermatitis and a long series of diseases.
Surprisingly, among the hereditary diseases are found some "useful" ones. For example, among some African nations there is an anomaly, which is called crescent anemia. It manifests itself in a change in the shape of red blood cells and causes the immunity of the owner of such an anomaly to malaria.
Sometimes there are cases when completely healthy parents give birth to a whole generation of sick children. This is due to the fact that each of us has a kind of gene ballast. These are genes responsible for the hereditary disease, but latent, suppressed by normal genes. It is extremely rare, but there are people with the same suppressed genes. In the case of such a meeting of "silent" genes, children with almost one hundred percent guarantee will receive hereditary pathology. That is why closely related marriages have been banned for many centuries, and incest among some peoples is strictly prohibited even now. So, for example, in Israel, even nowadays the future newlyweds should provide information about blood relatives up to the fifth generation before marriage. This helps to avoid incest and the occurrence of gene pathologies.
Hereditary diseases are not always manifested at birth or at an early age. Some deviations are found when parents pay attention to the delay in physical or mental development of a baby in the first years of life, some notice those only at school, some, such as Huntington’s chorea (progressive mental retardation), after forty years old.
- Since the origin of hereditary diseases lies at the gene level, today's medicine is powerless in the struggle against them. All activities that specialists can offer are aimed at alleviating the symptoms of the disease, socializing patients, special rehabilitation and training programs. The main way to combat hereditary diseases is to prevent them.
- When planning a family, genetics and physicians recommend adhering to a number of recommendations that we decided to give below.
- Do not delay the birth of the child "for later." The older the age of the mother, the higher the chance of having a child with Down syndrome is. This is due to the fact that this set of germ cells (eggs) given to mothers from birth is anomalously transformed with time and under the influence of a number of unfavorable factors. For example, in mothers of 16 years of age, the birth of a child with Down syndrome occurs in one case out of 1640, whereas in forty-year-old mothers this ratio is already 1:84.
- With the help of a geneticist, make a detailed investigation. Pay special attention to the diseases that your blood relatives and relatives of your partner have had. The specialist will assess the risks and give recommendations.
- In case of miscarriages or natural abortions in anamnesis, consult a geneticist. Often these pathologies are associated with fetal genetic abnormalities.
- Before adopting a child, check (if possible) the pedigree of a future member of your family. The best solution would be to carry out the karyotyping of the baby before completing the documents.
- During pregnancy, do not neglect the "triple test" and ultrasound. If the doctor sees the need, it is worth undergoing a chorion biopsy. This test will determine the chromosomal set of the embryo and detect gene abnormalities for up to 12 weeks.