Hereditary diseases

Hereditary diseases - diseases caused by disorders in genetic (hereditary) phone sex cells. Hereditary diseases caused by mutations (see Variability)arising in the chromosomal apparatus reproductive cells of one of the parents or in the more remote ancestors (see Heredity). There are chromosomal and genetic mutations. The first is caused by a change in the number of chromosomes (for example, the appearance of extra chromosomes, intra - and micromania restructuring and so on). The second is the result of changes in molecules of DNAthat form the basis of the chromosomes (see Nucleic acid). A hereditary disease characterized by the fact that can be repeated and subsequent generations or wearing a family character. Hereditary diseases associated with gene mutations that can be transmitted in three main types: autosomal dominant, autosomal recessive recessive and, coupled with the floor, type.
When an autosomal dominant pattern of inheritance is usually one parent is sick of the subject and his relatives. Hereditary diseases can be traced half of the children of the patient; both sexes are affected equally; in healthy individuals offspring remains healthy. Mutant gene is localized in one of asexual chromosomes - autosome. Examples of hereditary diseases transmitted by dominant type, can serve: arachnodactyly (see), some forms of myopathy (see), neirofibromatos (see), the chondrodystrophy (see), hereditary atrophy hearing nerves, tuberose sclerosis and other it Should be noted that in some cases the parent of the patient lacks the typical clinical picture of hereditary diseases, and revealed only individual characteristics that depends on the degree of probleemist mutant gene, is largely determined by its interaction with other genes and environmental conditions.
If a hereditary disease is transmitted in an autosomal recessive type, sick children can be born from seemingly healthy parents, but are carriers of the mutant gene, called heterozygous carriers. Mutant gene, located in one of the autosomes, is opposed to the normal gene to another of the same autosomes, which neutralizes the effect of the mutant gene, and he is depressed (recessive) state. When two similar recessive genes inherited from both parents, there is a state of homozygosity and develops a hereditary disease. The probability of such a meeting of two mutant genes is 25%. The disease is equally affects both sexes. When an autosomal recessive type frequency of hereditary diseases is increased in case a natural marriage, increase the probability of meeting of two mutant genes. Autosomal recessive type is of particular importance in hereditary pathology, because this type is passed to the majority of hereditary metabolic diseases: phenylketonuria (vinilpirrolidona mental retardation), amaurocichla family idiocy, galactosemia (see), hepato-lenticular degeneration (see) and a number of other diseases.
The transmission of diseases by recessive, sex-linked, type due to the localization of the mutant gene in sexual X chromosome. The woman who is the bearer of the mutant gene, clinically remains healthy, because the activity of this gene is compensated by the normal gene second X chromosome. However, half of its sons may have a hereditary disease, half daughters may be hidden carriers of the mutant gene. Hereditary diseases often found in the father, brother or nephew, mother. In recessive, coupled with the floor, type of inherited diseases such as hemophilia (see), color blindness, miopatia dushenna, etc.
In some cases appear hereditary disease caused by a chromosomal mutations (chromosome diseases). Each chromosome contains thousands of genes, therefore, a violation of a divergence of chromosomes during meiosis (see), leading to the emergence of gametes and then zygotes with an extra chromosome or, conversely, to the lack of it, in serious violation of the development. The body, which developed from a zygote, usually perish at the stage of the embryo or fetus, but in some cases survives and becomes a carrier of one of the heavy constitutional abnormalities, such as down's syndrome, syndrome of Kleinfelter or Shereshevsky - Turner, trisomy-X etc.
To manifest hereditary diseases may at any age. Many hereditary diseases develop in childhood, some of them are detected at birth or in the first days of a child's life: hemolytic disease of the newborn (see), congenital myotonia (see), galactosemia. In the first year of life is manifested phenylketonuria, spinal amyotrophy, hereditary-like syndromes, Niemann - pick disease, etc.
However, not all congenital disease necessarily hereditary. In particular, congenital syphilis is not hereditary, as occurs in the result of intrauterine infection of the fetus, and not in connection with hereditary caused by the changes of the genetic apparatus.
In early childhood emerge and acquire defined clinical picture of some forms of myopathy, tuberose sclerosis, gargoylism (see), and so on, In the preschool and school age can be found hepato-lenticular degeneration, neural amyotrophy, ataxia family ataxia (see), angiomatosis and other Individual genetic diseases occur at a later age, sometimes in senile. An example is chorea (see) Huntington. Generally, revealed a correlation between the time of occurrence of clinical signs of hereditary disease and its severity: the earlier to occur of hereditary disease, zlokacestvennoe its course. Along with a tendency to occur at a certain age and progressive course of a hereditary disease frequently characterized by systemic lesion of a number of organs and tissues.
There are some common features that can help you diagnose hereditary disease of metabolism. So, most diseases of the metabolism of amino acids characterized by decreased intelligence, seizures, a variety of neurological disorders. A typical example is phenylketonuria. Many disorders of lipid metabolism, in particular intracellular lipoids (see), Niemann - pick disease (see), Gaucher disease (see), amaurocichla idiocy, causing heavy damage to the nervous system, eyes and internal organs. Disease of carbohydrate metabolism often manifest hypotrophy, gastrointestinal disorders, liver enlargement (galactosemia, intolerance disaccharides). Metabolic mucopolysaccharides (gargoylism) leads to changes in the musculoskeletal system, hepatomegaly, the defeat of the cardiovascular system, the clouding of the cornea, dementia.
When diagnosing hereditary diseases should be aware of their prokopiak - non-hereditary disease, clinically resembling a hereditary disease. So, myopathy syndrome in collagenoses and some endocrine diseases should be differentiated from the true myopathy, the effects of trauma - from double acetosa (see), changes in the musculoskeletal system and internal organs in the rickets from gargoylism etc. Careful analysis of family history, genealogy and clinical symptoms of disease, monitoring the dynamics allow to establish his true nature. The final diagnosis can be improved with the use of additional methods of research (biochemical and other).

  • Treatment of hereditary diseases